How do I convince my parents to let me go to my girlfriend's house?

So we havent seen each other for a while and we want to see each other but since it's a school day i can't stay late. So we were thinking like 4-7 but i have swim practice from 5-7:30. I missed a day last week cuz we had midterms and I needed to study a little more so they only let me miss if I'm sick, have too much hw, or dead tired. How can i can convince them???