What should a girl who suffers from excessive gas and bubbles during prayer, and is compelled to repeat her ablution and prayers many times, do regarding her prayer and ablution?

If you doubt the reality of the bubbles—whether they are gas or not—and you experience frequent doubts, these do not affect the validity of your ablution (wudu') or your prayer (salat). Your purity (tahara) is not invalidated unless you are certain of the emission of gas, either by hearing a sound or smelling an odor. Things are presumed to remain in their original state until the contrary is certain. Therefore, completely disregard this doubt.