I am in a slightly similar position OP. I don't have a business that runs itself, but I do have a job that I enjoy but have been doing for many years now so I don't find it as challenging as I used to, and my DC are teens and need me a lot less these days (this is the key change for me), so I suddenly seem to have spare time on my hands. I work 4 days a week, and my day off was always busy busy busy trying to fit in everything on my to do list. In the last few months I've unexpectedly found myself sitting around on my day off without much to do! DH works long hours.
I could go full time I suppose. It seems a bit pointless though - we don't need the money and I'm in my 50s so I was expecting to start winding down career-wise rather than stepping up.
Cancel the cleaner? What would be the point of that - I hate cleaning!
Travel? I work 4 days and have secondary school age kids so not really an option (beyond the normal family holidays that we do anyway).
Volunteering? I do have a volunteer role, but I must admit that I don't actually find it that much more interesting / rewarding than my paid job.
Socialising? I have a fairly active social life, I'm happy with that.
Hobbies? I like exercising and I'm trying to increase that. I like reading and I already read a lot. I can't really think of anything else I'm passionate about!
Maybe I should just embrace the pottering, and not feel guilty / lazy / like I need a higher purpose!