Hi CPW,
Autoplay is on by default. Just to clarify, does that feature only turn back on after the Apple TV goes to sleep automatically, or does it happen at other times as well? That information will help us get a better understanding of the behavior you're experiencing.
Please check out the information in the following link, which outlines how to manage the Autoplay feature, and may be helpful: Now Playing: Control music playback on Apple TV
* Turn Autoplay off or on: Autoplay (on by default) continues to extend the queue with similar songs until you stop playing music. You’ll be able to see the next ten songs that are queued up. To turn Autoplay off, select the Autoplay button
so that the black dot disappears. To turn Autoplay on again, select the Autoplay button
again.
Thanks!