Clear ListView on Button Click (Post Back) in ASP.Net using C#

I have a form which uploads the file after uploading the listview should be clear.

i have used clear method but it did not get clear.

string Resume = string.Empty;
string htmlresume = string.Empty;
string mail = string.Empty;
int hrid = 0;
string cont = string.Empty;
string cont1 = string.Empty;
string firstname = string.Empty;
string Middlename = string.Empty;
string lastname = string.Empty;
string read = "";
string htmlContents = "";
string dobs = "";
string filesdata;
List<HttpPostedFile> files = Session["Files"] as List<HttpPostedFile>;
try
{
    HttpFileCollection hfc = Request.Files;
    for (int i = 0; i < files.Count; i++)
    {
        HttpPostedFile hpf = files[i];
        if (hpf.ContentLength > 0)
        {
            FileInfo fi = new FileInfo(hpf.FileName);
            string ext = fi.Extension;
            string sFileName = Path.GetFileName(hpf.FileName);
            string sFileExt = Path.GetExtension(hpf.FileName);
            sFileName = sFileName + "_" + DateTime.Now.Ticks;
            sFileName = sFileName.Replace("@", "_");
            sFileName = sFileName.Replace(".", "_");
            sFileName = sFileName.Replace("/", "_");
            sFileName = sFileName.Replace(" ", "_");
            sFileName = sFileName.Replace(":", "_");
            htmlresume = sFileName + "." + "html";
            sFileName = sFileName + sFileExt;
            var output = Regex.Replace(sFileName, @"[\d-]", string.Empty);
            string[] splittedArray = output.Split(new char[] { ',', '_', '-', '.' }, StringSplitOptions.RemoveEmptyEntries).Select(x => x.Trim()).ToArray();
            if (splittedArray.Length >= 0)
            {
                firstname = splittedArray[0];

            }
            if (splittedArray.Length >= 1)
            {
                Middlename = splittedArray[1];
            }
            if (splittedArray.Length >= 2)
            {
                lastname = splittedArray[2];
            }

            //load file in folder
            hpf.SaveAs(Server.MapPath("~/uploads/files/Documents/") + System.IO.Path.GetFileName(files[i].FileName));
            string DT = System.DateTime.Now.ToShortDateString();

            //  Document parser code
            aspose parser = new aspose();
            parser.mail = mail;

            if (mail != "")
            {
                //INSERT INTO HR_INFO TABLE
                int rowAffected2 = DAL.InsertIntoPersonal_Info("7", "0", mail, firstname, Middlename, lastname, "1", "1", "1", "1", cont, cont1, DT, "Show");
            }
            else
            {
                System.GC.Collect();
                System.GC.WaitForPendingFinalizers();
                File.Delete(Server.MapPath(Server.MapPath("~/uploads/files/Documents/") + System.IO.Path.GetFileName(files[i].FileName)));
            }
        }
    }
}
catch (Exception)
{
    throw;
}

Session.Clear();
Session.Abandon();
lstview.Items.Clear();
lstview.DataSource = null;