the first thing I would do is to find out what your coach has planned for the fall. Your summer mileage base is very good and will set you up for success this fall.
After July 4th, you'll want to add tempo runs and some hill repeat sessions to the mix. The tempo runs should be either 4 miles or 20:00 in duration. Run a pace that is comfortably hard. You should not be able to hold a conversation during this run, but it should not be all out. For hill sessions, try to find a hill that will take you at least 60 seconds to run up. Jog the downhills very easily. Start with 6 and increase by two each week until school starts.
To give yourself a little variety on tempo runs, you could also do structured fartlek runs (various surges within a run). You could start with 10 x 60 seconds hard/60 seconds easy or 6-8x 2:00 hard and 1:00 easy. The pace should be at 5k effort for the 60/60's and at 10k effort for the 2:1 workout. You should be able to run consistently for all reps, so don't kill them, but like the tempo run, you need to run hard enough to not be able to hold a lengthy conversation. Also, during the summer have 1-2 days per week in which you run some 100 meter accelerations after some of your medium length distance days just to keep in touch with your top end speed.
Ideally during the season, you can move to interval type training in which you run repeats ranging from 400 meters all the way up to one mile repeats at or even just a bit faster than your current race pace. I'm presuming that you are running 5k for your distance. So if you are running 1000 meter repeats, your goal pace for 20:00 would be about 3:55 per 1000 since 4:00 pace would yield 20:00. But, if you begin the season running 25:00 for 5k, your pace would 4:55 since that is 5:00 per thousand. So the pace of your intervals should get faster as the season goes on and your times start to drop. The races themselves should help you get to a higher level of fitness.
Good luck, let us know how it goes.