For the first attempt at bringing in physical aspects for him, I decided to try his hopping and jumping, and trying to get him to get better at both.
Hopping is just a matter of trying to capture it, but he needs to do it more consistently to make that more likely. For now, he still needs something to motivate him to try reaching. I didn't want to use food as the lure as this is a good chance to make an object more rewarding and desirable.
I used one of his rabbit skin strips, and he was certainly attracted! After a bit of teasing, he stood up on his back legs, but didn't make any hops.
I encouraged him to "get it" and he did start hopping. I lifted the object up more and moved it around to get him really tracking it. Once he hopped up to get it, I let go and let him shake it. Then I gave him a click and a treat and started again. Now, he was twice as into it, and started getting higher off the ground and hopping more steadily. Still need some work, but this was a good effort, and I didn't want to wear him out for the jumping.
Now the jumping, that's a different story. He wasn't certain of it, and I think part of this is because he's lost judging the distance past the jump. I think he was as much uncertain of that as he was of the hoop again.
He tried to go around the hoop, like he did way back in the beginning. After much urging, he started jumping through the hoop. I clicked while he was in the air going through the hoop, and rewarded him when he landed.
He got more motivated, but still, he was hesitant. Looks like this is something that will really need to work on to get him back where he used to be comfortable with the hoop.
He also used to jump "in" the hoop and then back "out" the hoop if I held it a little above the floor and flat. This time, though, he totally refused.
That's good, though, because it shows me where he needs work and what we need to keep working on, and that means more chances for the both of us to grow.