Well, Frozen worked extremely well as a musical and pretty much all the songs were awesome, (except I'm not so keen on Fixer Upper). I think not having any songs in the sequel at all would be weird, but it'll be hard to beat the original's soundtrack. Though I've read that Robert and Kristen Anderson Lopez are back to write the songs for the sequel, so they should be good. Maybe one or two less songs? Sometimes too many songs can halt the story in the film.
Depends on the film though. Mary Poppins has 16 songs and they don't ever feel like they halt the story, just glide it along.