using System;
using System.Collections.Generic;
using System.Xml.Linq;
using System.Text;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;
using System.Globalization;
using System.Xml;
using System.Collections;
using System.Linq;

namespace SampleSharePointSolutions
{
    public class UpdateFiles : SPFeatureReceiver
    {
        public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
            if (properties != null)
            {
                using (SPSite currentSite = (SPSite)properties.Feature.Parent)
                {
                    using (var web = currentSite.OpenWeb())
                    {
                        var ElementDefinitions = properties.Definition.GetElementDefinitions(CultureInfo.CurrentCulture);

                        foreach (SPElementDefinition ElementDefinition in ElementDefinitions)
                        {
                            if (ElementDefinition.ElementType == "Module")
                            {
                                Helper.UpdateFilesInModule(ElementDefinition, web);
                            }
                        }
                    }

                }
            }
        }

        public override void FeatureDeactivating(SPFeatureReceiverProperties properties)
        {
            //// throw new NotImplementedException();
        }

        public override void FeatureInstalled(SPFeatureReceiverProperties properties)
        {
            ////throw new NotImplementedException();
        }

        public override void FeatureUninstalling(SPFeatureReceiverProperties properties)
        {
            //// throw new NotImplementedException();
        }
    }

    internal static class Helper
    {
        internal static void UpdateFilesInModule(SPElementDefinition elementDefinition, SPWeb web)
        {
            XElement xml = elementDefinition.XmlDefinition.ToXElement();
            XNamespace xmlns = "http://schemas.microsoft.com/sharepoint/";
            string featureDir = elementDefinition.FeatureDefinition.RootDirectory;
            Module module = (from m in xml.DescendantsAndSelf()
                             select new Module
                             {
                                 ProvisioningUrl = m.Attribute("Url").Value,
                                 PhysicalPath = Path.Combine(featureDir, m.Attribute("Path").Value),
                                 Files = (from f in m.Elements(xmlns.GetName("File"))
                                          select new Module.File
                                          {
                                              Name = f.Attribute("Url").Value,
                                              Properties = (from p in f.Elements(xmlns.GetName("Property"))
                                                            select p).ToDictionary(
                                                              n => n.Attribute("Name").Value,
                                                              v => v.Attribute("Value").Value)
                                          }).ToArray()
                             }).First();

            if (module == null)
            {
                return;
            }

            foreach (Module.File file in module.Files)
            {
                string physicalPath = Path.Combine(module.PhysicalPath, file.Name);
                string virtualPath = string.Concat(web.Url, "/", module.ProvisioningUrl, "/", file.Name);

                if (File.Exists(physicalPath))
                {
                    using (StreamReader sreader = new StreamReader(physicalPath))
                    {
                        if (!CheckOutStatus(web.GetFile(virtualPath)))
                        {
                            web.GetFile(virtualPath).CheckOut();
                        }
                        SPFile spFile = web.Files.Add(virtualPath, sreader.BaseStream, new Hashtable(file.Properties), true);
                        spFile.CheckIn("Updated", SPCheckinType.MajorCheckIn);
                        if (CheckContentApproval(spFile.Item))
                        {
                            spFile.Approve("Updated");
                        }

                        spFile.Update();
                    }
                }
            }

        }

        private static bool CheckOutStatus(SPFile file)
        {
            if (file.CheckOutStatus != SPFile.SPCheckOutStatus.None)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        private static bool CheckContentApproval(SPListItem listitem)
        {
            bool isContentApprovalEnabled = listitem.ParentList.EnableModeration;

            return isContentApprovalEnabled;
        }

        public static XElement ToXElement(this XmlNode node)
        {
            XDocument xDoc = new XDocument();

            using (XmlWriter xmlWriter = xDoc.CreateWriter())

                node.WriteTo(xmlWriter);

            return xDoc.Root;

        }
    }

    public class Module
    {
        public string ProvisioningUrl { get; set; }
        public string PhysicalPath { get; set; }
        public Module.File[] Files { get; set; }

        public class File
        {
            public string Name { get; set; }
            public Dictionary<string, string> Properties { get; set; }
        }
    }
}

http://vivek-soni.blogspot.com/2009/07/overwriting-files-using-module-element.html

Overwriting Files in SharePoint using Module Element

sharepoint

C#