All After Effects users will eventually need to learn how to loop animations. If you don't learn how, you'll be stuck copying and pasting layers over and over, which can be incredibly messy. Thankfully, the process is really simple and can be done in under a minute. Let's begin, shall we?
(Side note: if you can't see the picture, click "i" button in the top left to enlarge it.)
So here I have a looping bubble animation. Before we begin, make sure that you create a new composition only for the animation. Do this by going to composition > new composition, and then create exactly one cycle of the animation in this new space. As you can see, my composition is called "snorebubble".