You’ve stumbled upon the school example of when to use ajax and when not to. You should only use ajax if refreshing the page will yield the same results, at least that’s how I see it (and probably a lot of people will agree with me).
That said, there are workarounds using javascript, but you’ll have to implement and handle it in your rails app yourself:
http://exanimo.com/javascript/using-the-statemanager-in-ajax-apps
Best regards
Peter De Berdt