I have a simple comp animating multiple layers and a camera in AE7. All the layers derive from a Photoshop CS2 file.

If I edit the layers in CS2 and save it, is there a refresh button or something I can hit in AE7 to get it to recognize the new edits?

Yeah, just right clicking on the file in the project bin/panel and selecting 'reload footage' does the trick I think. Not sure if you have to do it each time for the individual layers though

I think it might be a little different with a Comp. In my case the layer names change, from merging or whatever, and reload doesn't work. You have to go into the folder in your project window, which has all the layers of the .psd comp file. Then reload (or even replace) the layer there.