Ultimately, side slip or speed brakes. In a glider those are essentially the only methods of reducing total energy. (Actually, the third is aggressive manoevering, as in aerobatics, but that's not exactly suitable while trying to land.)
By increasing your speed you will initially increase ROD as well, but that will be offset if you reduce speed later on - you're only exchanging kinetic for potential energy and vice versa. Furthermore, the descent angle (glide ratio) will not change all that much with speed to have any meaningful effect. Well, at least in the frame of reference of powered flying. Glider pilots fight for every scrap of lift, and there's a whole body of theory around selecting the optimal speed for various circumstances.