A hot horse is not a horse with too much energy. He is a horse whose tension has nowhere to go. It builds in his body, and movement is the only outlet he knows: jogging, rushing, running through the hand. Everything we usually do, holding him, circling him, tiring him out on the lunge, contains the energy without giving it an exit. That is why it works for a day and is back the next morning.
We give the energy a door. He learns to let tension out through his body instead of through his feet, starting with release work in the saddle and the shoulder as the exit. Then you rehearse your actual ride from the ground, so by the time you mount, he has already answered the question that used to set him off.