How do i convince my mom to let me get my lip periced?

ive wanted my lip periced since i was 10 and now im 14 but my mom still wont let me get it and i have 3 on my ears and a barbell and my belly button but ive wanted my lip more bt she dosent like it because its on my face and she said she will think about it if i get my grades up and show her responceibilty but im out for summer and i dont want to waite 3 months and also she thinks it will get infected?