How to update cached versions of xmls and swfs

[COLOR=#333333][FONT=adobe-clean]Hi.[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]I am developing an online virtual world to teach English. The good thing about flash is the browser caché so you don’t wait for eveything to load everytime BUT I am having problems when I update a file. If I don’t empty the caché then the old file is loaded and the new one ignored. There must be a solution to this otherwise people will always end up with an old version of all my files. We CANT expect a client to clear his/her caché obviously. I have never been asked to do that by any online product but I sometimes see updates so there is a way.[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]Cheers in advance for any help.[/FONT][/COLOR]