Does anyone know the mechanics of this? Does the provider have to contact TER with some proof that she has reentered the business? There are no new reviews for this lady.

It depends on the reason they were delisted in the first place but many come back. They have to prove to TER who they are and that the reason for the delisting no longer applies.

Every time I see this I think of the old Steven King story, Sometimes They Come Back -- not what any of us want....