(2) During the ascent, Xiaohong's velocity is unchanged, so its kinetic energy is unchanged and its height is increased, so its gravitational potential energy is increased, so Xiaohong's mechanical energy is increased;
(3) In the process of rising, Xiaohong carried her schoolbag and exerted a force on it, which passed a certain distance along the direction of the force, so Xiaohong did something for the schoolbag.
So the answer is: still; Increase; Did some work.