I like to continue on in an easy gears spinning the lactic acid our of my legs while getting a few good deep recovery breaths.

Then soft pedal down on the descent to make sure the legs don't freeze up while using the momentum to carry me up at least part of the next hill. If I'm tired, I use the descent as recovery and gear down to continue climbing when I feel the right amount of resistance on the next climb.

Honestly, I rarely ever push on a descent. That is recovery time used to conserve energy for the next climb.