they will not make you pay it back even if your 2020 numbers end up being too high. If you already filed for 2019, then you are hosed unless you make less than the cutoff in 2020.

Quitting your job definitely could work, but I assume the disruption of life and income isn't worth the 1-5k you'd get from this. Unless....you can get let go instead of quitting and then collect the unemployment. Sort of goes against the spirit of it all, but hey, when is there ever a government program that won't get abused.