I recently rode a very headstrong horse. He would get very excited when we were jumping, he wouldn't stop at the end of the course and would drag me through gates. I started bringing him into a circle and gradually making that circle tighter until he would finally stop. I also did a lot of transitions in my flat work and practiced halting from the walk, trot, canter, and would throw in ground poles and small jumps. I would even try to do figure eights and serpentines before jumping to release some of his energy and make him more soft and supple in the mouth. This helped enormously and I could more easily stop and control him.
If you pull on the reins and she doesn't stop turn her in a small circle and if she doesn't turn lightly jerk on the bit on the side that is the inside of the small circle and turn her until she stops and she's just walking to turn and then stop and back her up about 4 steps and walk forwards.
Lots and lots and lots of transitions. Go back to some flat work as well, instead of jumps just do ground poles and make her stop after the pole and then have her back up 2 steps. And don't always ask her to stop in the same spot. Try like 15 steps after the pole and then like 3 steps and then 7 steps mix it up so she isn't expecting it. But also make sure she understands and doesn't pull through the stop. Try lifting your hands alittle bit and squeezing leg to help get her to stop. Many people people leg means to go but when you add leg to her to make her stop it helps the horse feel as though they won't trip or fall and collapse. You can also instead of going all the ah around the ring to get to the pole again either set up multiple poles around the arena or have her simply turn around in the spot she is and trot right back over the same pole and then stop after it again.
Before jumping in your warm up do lots of transitions. Both upward and down so she's listening. If she doesn't listen and is being totally disrespectful then turn her into the wall and force the stop. When your practising the stop make sure to instantly give a release once she stops even if she stops for a second then pick right back up again. She will learn that she will be rewarded. While jumping you can always jump a line and force a stop by a wall or you can jump then down ward transition between jumps. If she is rushing put trot poles out and make her trot. The slower pace will help with the stop... I hope that all makes sense!
Go back to groundwork. Get her supple to pressure and focused on you before riding again. Lots of lunging, changing directions often. Flexing, yielding, and backing. I found backing to be most beneficial to my gelding. I backed him in and out of his stall, in and out of the wash room, in and out of gates, etc...