1.  Rate your performance on a 1-10 scale with 10 being the best.
2 . Explain the rating.
3.  List any injuries and/or physical factors - good or bad.
4.  List any mental and emotional factors - good or bad.
5.  List any environmental factors that influenced your race - good or bad.
6.  Briefly describe the start, the middle, and the finish of the race.
7.  List any mile splits.
8.  Discuss ways to improve your performance.
9.  You are communicating to the coach and your future self.
Do your recap soon after each race.  
You are documenting your endeavor for posterity.
It should not take more than 15 minutes.
Race recaps are required, especially for PE credit, and varsity letter status.
Race recaps are due to me by Sunday night each week, but preferably the night of the meet.
Keep your recaps in an electronic format, in one document (separate from your training log) with earliest race at the top of the document.