Times like this call for sharper shorter aids. If she takes a long time to respond, you sometimes need to give her a sharper tug to get a quicker response. But in doing so you need to release a lot faster and not just sit there holding her mouth. That’s when horses tend to ignore your hand and keep going. Try a few short tugs with your reins and the minute she comes back release and give her a pat. If you are trotting do lots of trot walk/trot halt transitions to keep it interesting. Remember stopping comes from the leg not nexcessarily the hand, so if you have a good trot where she’s working from behind, you’ll find stopping much easier with these short tugs. You’ll find her responding much better after. If she also opens her mouth a lot, try a loose flash noseband to help her stay in contact with you.
I love to use half halts with my outside rein, soft bit so you can be a bit more stern! Good luck😊
My horse does not listen when I ask her to stop. I have to pull on the reins much more than I would like to and then she will keep walking with her mouth open and then stop.
She is in a snaffle right now, so a really soft bit. I have also tried to sit back further when I ask her to halt and that doesn’t help much either