One thing to try is counterbending. If you ride Western, you'll want to post the trot and take her down to a snaffle (if she's not in one already) for this. Ride her at a trot on a clockwise 20m circle and ask her to bend around your inside leg. Don't exaggerate her neck bend, just enough that you can see her eye. After several strides of her giving you this bend, ask for her to counterbend to the outside by sitting a beat so you are on the WRONG diagonal, transferring some weight to your outside seatbone and stretching your left (outside leg) down to ask her to bend her body around it. Ask her to give her head to the outside a tad, so her body is bent like it would be if you were tracking left. However, you're going to stay on the clockwise circle.
After half a circle or so, switch your bend by sitting a beat to come up on the correct diagonal and applying the aids to ask her to bend around your inside leg. You may need to open your outside rein a bit if she has a tendancy to overbend or drop her inside shoulder.
Continue like this until she's responsive to changing her bend and there's no resistance or leaning on your hands. This is a great warmup for my eventer in particular, and he loves it--comes down nicely on the bit a few minutes into the exercise and really starts to drive from behind. Once you feel like she's really bending nicely to the right, apply the aids and ask for right-lead canter. If she doesn't get it, just bring her back down to trot, balance her again, and ask again. If she becomes frustrated, take a break and come back to it.
Practice your forehand and haunch turns. You may need to start them from the ground, but being able to push her haunch over is a good introduction to leg yields, which will be valuable in pushing the haunch over when you ask for canter.