Board Thread:Character Discussion/@comment-3574574-20180202212004/@comment-25375217-20180202212447

It's never made clear, unfortunately. She does refer to getting her wand which would explain how she has magic (she doesn't, but the wand does), but then she's never seen using a wand, so who knows.

I presume she got her magic back somehow and we'll find out how exactly at some point in 7B.