I also think it will be Spa Day, and am looking forward to it. It's a very good pack, but does indeed feel a bit small for a GP.
Refreshed and clean could mean skincare. Skincare products might be made from basegame flowers and fish, with a few additional options for owners of more packs. (Come to think of it, didn't Spa Day come with three new fish?)
Or maybe a new wash hair feature where sims can now dye their hair without changing their genetics. Painting nails and toes. Some new effect for the meditation feature, although I cannot think of one at the moment.