I was living with my parents when I first adopted my bunny (so it was his second home, not his first). He was about 5 months old when I adopted him. He started showing happy/comfortable body language (zoomies/binkies/flops) relatively quickly, and continued to show it. Each morning, after getting his morning pellets and being let out to play, he would binky without fail.
We moved about 6 weeks ago to an apartment. He was initially kept in my bedroom when I lived with my folks, but he is now kept in my living room (much bigger space for his playtime!). He doesn’t seem especially interested in exploring beyond his little play area that I’ve set up with rugs/mats/toys. I do see him flop/loaf pretty often, so I know he’s comfortable at least, but no more binkies. 
What’s very interesting is that this week, I’m house sitting/dog sitting for my parents while they’re away, and of course I brought my bunny along. We are staying in my old bedroom (I have a big x-pen set up instead of his big hutch) and he’s started binkying again in the mornings! He seems a bit more spritely in general here. I wonder if it’s that he’s in my bedroom with me again? Or maybe that my parents’ dog is around for company? They’re not exactly friends, but they seem very comfortable around each other (sometimes even lounging together on my bed, not very close together, but still), and he’s a solo bun.
Any tips on how to acclimate him more to the apartment? Should I move him back to my room? (I’d prefer not to since my new bedroom is very small, but if it’s better for him, I’d do it.) Should I get him another non-bun companion? (Landlord said no to a second bunny, but yes to a cat or small quiet dog – not sure why. I’ve told him the bunny is fixed so I’m guessing he’s worried about potential damages). Advice in general would be appreciated!