Car's front bumper paint dull?

I have an 05 Toyota Corolla and it's a cactus mica color. The front bumper is dull and I've tried waxing and polishing it but it still looks the same. It seems like the previous owner took a can of spraypaint and painted over the clear coated part. Should I buy clear coat and go over it? Is there any other type of clear coat besides the spray ones at Autozone?