setXMLFile Any way to load in a new file?

Hiya, If have my xml menu load in no problems, however I want to load in a new menu.
The menu loads with:
hm being the clip it loads to.

When i click an item, I want to change the xml file to say:

i know this isnt the right code, my question is do you have to unload the clip & if so how do I load in a new one?.

Any links/help will be very appreciated!.