There is an end, yes, and it happens a little bit after consuming all of the universe. You'll know that you've reached it when you are offered the option to delete all of your progress and restart.

As with many of the better-designed incremental games, there are moments in UP where you might get the impression that the way to continue is to just do more of what you've been doing, but actually the way to continue is to do something slightly different. I think you're referring to the starkest of those.