This is a fun way to combine different game genres. But I felt I wanted my success to matter more. When I failed, I was only losing a few dollars, so it didn't really matter. As a thought excersize: what if they multiplied? So I really wanted to be as perfect as possible.
I also found the difficulty wasn't quite right as I was upgrading. E.g, I might ace slicing repeatedly until I finally get enough money to actually make it hard. Maybe there could be discounts for the difficulty upgrades if you're consistently doing well?