Takeoff Altitude Questions

I often fly in a valley with cliffs. At the bottom of the valley where i takeoff I can go to 391 (400) feet which is about 20 feel lower than the cliff edge. Today i flew from a higher point in the valley (about 150’ higher) but the drone still topped out 20 feet lower than the cliff edge. Can the takeoff altitude be reset to a new altitude?? Would love to get “over” that cliff edge!!