Yeah, as long as he's within a certain vicinity, he can bring them back. Like I said, it's never explained properly, and is kept quite vague in the books, maybe someone like Bran can enlighten us at some point.
Hardhome was the first time we actually saw him do it in person if I recall. (God I love that episode)
Give over with that ****ing episode, it's not on Sky and I can't watch it again (must have been pissed first time)