Did you finish Kaplan ?
if so, do it again, I am quite confident that you will still make some errors...
frankly I consider that it is better to do 50 exercices, taking time to analyze your errors and do it until you totally understand the solution than doing 500 exercices but you don't really check why you were wrong...
But I think you can find a lot of problems on this website, and if you add Kaplan it should be enough for the difficulty ^_^