C# drop down list Databinding

I have a C# DropDownList that I set the DataSource for in the following way in the OnPreRender() method.  What happens is that after the user changes the value in the drop down list, the page refreshes, and the data source re-fills the DropDownList correctly, but automatically goes back to the first value.  I was just wondering how to make this so that it stays with the value the user selected.

 protected override void OnPreRenderComplete(EventArgs e)
    {
                SqlConnection sqlConnectionString88 = new SqlConnection("Data Source=server;Initial Catalog=database;Persist Security Info=True;User ID=userid;Password=password");
        sqlConnectionString88.Open();
        SqlCommand cmd88 = new SqlCommand();
        SqlDataReader reader88;
        cmd88.Parameters.Add(new SqlParameter("@Proj", SqlDbType.Int, 10));
        cmd88.Parameters["@Proj"].Value = projectselected;
        cmd88.CommandText = "SELECT column1 FROM table1 WHERE column2 = @Proj AND column3 = 'False'";
        cmd88.CommandType = CommandType.Text;
        cmd88.Connection = sqlConnectionString88;
        reader88 = cmd88.ExecuteReader();
        DropDownList2.DataSource = reader88;
        DropDownList2.DataTextField = "VersionName";
        DropDownList2.DataBind();
        reader88.Close();
        sqlConnectionString88.Close();

        GridView1.DataBind();
    }