How do I improve my mile and a half time?

I am a sixteen year old incoming junior, and my dream is to go to the United States Naval Academy. I want to be a leader and I want to serve my country. I make all A's. I take AP and honors classes. I play varsity football and start. I am an eagle scout. I'm in NHS. I'm kind of big (6'0 225 lb), but I have 18% body fat. I'm strong and I'm not worried about push ups and sit ups. However, I'm kind of concerned about my distance running. I run at about an 8min 30sec mile pace, which is certainly not on track for the required 10:30 for the 1.5 mile on the PRT. I've taken to running the five mile trail by my house on my off days during the off season (tuesdays and thursdays). And normally have a one to two mile run for conditioning on Mondays, Wednesdays, and Fridays. I'm just wondering if anyone out there has any suggestions for how I can improve this. Thank you