Another thing you can do in the first jhāna is play with the intensity level of the pīti. Once you’ve gotten to the point where you can stabilize it, see if you can decrease the level of intensity of the pīti and then bring it back up. You are, so to speak, finding a sort of mental volume control for the pīti. It is easier to bring the pīti down and then back up than it is to try to pump it up higher still.
