14 year old running 27 in the 200 and 63 in the 400 how can I improve

I just finished my 8th year of track and I'm wondering on how I can improve during the school year to prepare for the season. I'm an upcoming freshman and I plan to do indoor and outdoor track. I have been just running 2 miles everyday this summer and doing basic sprint workouts but haven't seen much improvement. In highschool I would like to stop running the 400 and transition to the 200 and 100. Any advice would be helpful thank you