Welcome to the forum Jessica!! Now keep in mind that I am not a barrel racer and have never run the pattern. What kind of bit do you have him in right now? As is always suggested here before going to a stronger bit, you may want to take him back to the beginning and start the pattern from a walk. Work your way slowly up to speed and make sure that you have perfect control over his head, body, and speed at each gait. Try walking and trotting the pattern some and switch things up sometimes. Maybe walk the first barrel then go lope some circles around the arena then go trot the third barrel and exit the arena. Just keep things interesting where he actually has to pay attention to you instead of concentrating so much on the pattern.
Again, I am by no means an expert but I am just throwing ideas out that may help a bit.