You can just use the appcache file to control the "max-age" of all of your web content directly. If you have dynamic access to the HTTP headers you can dynamically set these. I use Apache's mod_headers to do it for me.
See: http://metaskills.net/2006/02/19/how-to ... -apache-2/
Alternatively, you can include a "version" tag in your javascript or html that if it doesnt match the current version you can trigger an update manually in C2.
Or you can do a URI-based version control system, like:
www.example.com/game/client/v1.49.4556