What you are looking to do is, as Kalon said, best handled server-side, specifically using HTTP response headers.
If you are using PHP, that's what the 'header' function is for.
See their second example:
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); // Date in the past
Should work flawless every time. In addition to that if this is a form/submit you don't want repeating, I would store a semi-random hash in a database md5(random.IP Addy.timestamp) and in a hidden input on the form on the page you don't want them going back to. When they submit the first time, delete it from the database. If the hash is submitted and isn't in the database, you'll know the form was submitted more than once.