How do You get adhesive off of Lexan?

I have my youngest daughter working in my shop to teach her work ethics, how to be handy, and for spending money.

I had errands to run and asked her to use the heat gun to warm up stickers on race car and pull off. When I got there she had the stickers off, but the adhesive was there and she was scraping off with single edge blades before I stopped her. Turns out the heat gun was tripping the circuit so she didn't use and pulled off cold.

Years ago my son used adhesive remover and that clouded the Lexan, so that isn't going to work. Any ideas?
Author: BK