Of course, man! I recall in high school having a PR of 18:34 after my first year, then I bumped up the mileage over the summer and got down to 16:53 the next year at states. Remember, consistency is key! You don't necessarily need really high mileage, just make sure you're getting in solid runs and not taking multiple days off at a time. One day of rest is fine, obviously, just try to avoid those random 3-5 days off periods that people sometimes have over the summer when they get lazy. Even if you're feeling lazy, get out there and try to get in 30 minutes at least. Good luck!