No bit is going to fix a horse that runs through bits. Instead of putting a band-aid on a bleeding artery stop jumping, go back to basics and fix the problem. Horses do not have hard mouths they have stiff bodies. Start back with the basics and so lots exercises to soften her body. Get control of her five body parts: head and neck, shoulder, rib cage and hind end; and the running though the bit problem will take care of itself.
Putting a stronger bit on her is doing her a disservice and setting yourself up for a wreck. Take the time now and fix the problem.