Trot poles are perfect for this!
If you have a dressage whip you can tap her back legs after every 5 steps. It'll make her learn to use her legs correctly. But then also make sure you keep the same pace, use a half halt when you tap her leg, though make sure your leg is still on. You don't want her speed to change. Also do cavaleties starting with 6 poles. Make sure you watch your posting and make sure it stays consistent
As well, depending if you sit or post, make sure your seat is consistent. That you're posting has the same, consistent rhythm.
Lots of half halts, working on trotting for lengthened periods of time ~10 minutes, making different shapes with changes of rein. You could also try going through one or many trot poles at an easy distance.
I had the same issue with mine and I began doing 10 minute long trots and after you do it consistently, you quickly see results. (I did anyways)