Change computer Apple TV uses to connect to iTunes

Question

I have the newest version of Apple TV. Firmware is up to date.

I set it up in the apartment I used to share with my girlfriend until about a week ago when I moved away for school. After I left, she found herself not only without companionship but also unable to access Netflix or the iTunes store.

I'm guessing this is because I set up the Apple TV using my mac, which is no longer in the apartment with the Apple TV. Assuming this is the case, I'm wondering: is resetting the Apple TV and going through the setup process again the best way for her to "associate" her mac with the Apple TV? Or is there an easy way to do this that won't wipe out all of the configurations we've made?