On page refresh need drop down list auto selected to previous value

This page has a drop down list.  The user selects their website from the list.  After the page displays a gridview, there are sometimes a button that can be pushed to fire off an email.  AFter this happens the page refreshes and every time the user has to reselect the website  they were working with from a drop down list.  How can I "pin" down the dropdown selector and have the previously selected website selected automatically and have the gridview refresh?
THis code is at the end of the button click where they push the button. It calls itself. adv_links_view.aspx
UpdateAdvLink(advlink)
                            Response.Redirect("adv_links_view.aspx")
                     &nbs ...