I can't preform my best through out an entire track meet?

At my state competition I started out by splitting a 1:58 in our 3200m relay. Yet later in the open eight I struggled to hit a 2:01. Plus at the regional competition I hit a 49 400, yet could only muster a 52 at states. What are some things to help me preform better through out the meet? Like training/meditation. Anything!