Re-painting foliage eraser [SOLVED]

Hi. I'm working on a terrain and have some foliage assets on some materials. I've figured out how to mask out the foliage area by using the erase foliage tool. However, I can't figure out how to undo that without using ctrl-z. Can I re-paint in the foliage that I have masked out? Maybe I've cleared out a large circle of foliage, but I want to add in some in the middle, or make the edges less uniform. How do I do that without hoping masking out was the last thing I did, and just undoing it and re-doing it better?

Update: I found the solution. By holding the "Alt" key, I can repaint the terrain to remove the mask the hides the foliage.