Are you sure it's the ATV at fault? Mine's been running for months and never lost connection. Is it a known issue or something?
I've done quite a bit of research.
There's tons of people complaining about this everywhere (official Apple forums, Macrumors the ones I checked the most).
It seems things stopped working for many after iOS 5, but it's not clear if it's an AppleTV issue or an iTunes one.
Supposedly, 5.0.1 (IIRC) on AppleTV should have solved that, but there's still plenty of issues left.
It's one of these problems that some claim to have solved by "having a specific version of iTunes", "having a specific version of iOS on ATV", "having a specific router", "having some specific ports forwarded"...
You know, no true solution anywhere.
It's a shame because I can't stream video, pictures or audio for (usually) more than 20 minutes before it loses sync.