This isn't the right approach for obvious reasons. The correct way is to disable caching of your web page.
You can use these META tags inside your HEAD element.
<meta http-equiv="Expires" CONTENT="0">
<meta http-equiv="Cache-Control" CONTENT="no-cache">
<meta http-equiv="Pragma" CONTENT="no-cache">
Or you can do it through your code-behind like this:
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetExpires(DateTime.Now);
Response.Cache.SetAllowResponseInBrowserHistory(false);