I have received numerous donations in the past. They were never accompanied by any specific request to fix something or make a feature. So even if I wanted to do something in the software out of a sense of obligation to those users, I would not have known what that is.

Realistically, a $100 donation doesn't get much of my time anyway.

It's more of a pat on the back; people like what you're doing, and the way you're doing it; so keep going. (Don't do anything differently, just more of it.)