title: Facebook access_token: how do I get it once the user accepted my app?
body: <p>When a user visits my site which contains a facebook app the first time, it requires him to allow it and he gets promted to do that, then I get the code which I can convert to an access_token. So far so good.</p>
  
  <p>But how do I get the token once the user has already visited the site?
  As long as this token form the first time is active everything is fine. But how do I get another token when the user had already allowed the app a week ago and is only visiting my page again?</p>