I think going bridleless would be a fun challenge for you, from your avatar it looks like (correct me if I'm wrong!) you are already riding bitless. Start out with some kind of ring or rope around her neck and keep your bridle on, but use it less and less, of course do it somewhere closed in and only if you trust her and feel in control.
Another thing we have at our barn is a large exercise ball that the horses like to push around. Another boarder was pushing it around with his horse and sidepassing over it while my mare and I were schooling dressage and my mare got all snorty and terrified, so the guy slowed down his mare and let my mare investigate and get closer and closer, until I was able to get her to roll it too! We had fun playing "soccer" and the mares were both having a blast too. I'll have to get some video, his reined cowhorse is maybe 14hh and she side passes over it so that she actually has to squish it down to it between her belly and the ground, she is a very broke horse! My 15.3hh girl didn't want it where she couldn't see it straight on, but it was definitely "outside the box" for her!
In this heat, I have been just doing some massage and stretches, it's uncharacteristically warm for MN so we have been hanging out in her stall under her fan. I do all her treat stretches and grooming in there and then got this little massager plastic thing and use it along her neck, withers, shoulders and haunches and she loves it!