increased speed into the ground effect, and then using the ground effect to strech the glide can also be an option....
... but sometimes a fatal option. A friend of mine was undershooting in a glider and tried to stretch his glide, to avoid the inconvenience of landing off the airfield. He flew in ground-effect over a perfectly landable field and then tried to hop over the boundary fence. He didn’t have enough energy and the barbed-wire sliced through the canopy.