Leave them on, expose to filtered light and they will green/red up and be fine. I left mine in a well drained pot all winter outside and have leafed up already.

I have left mine in the ground for the last 2 years, they're just coming up now, nice and green, but it only got down to minus 10c this year and last, Derek.

I don't lift mine and they seem to come back every year ok. I didn't know you were supposed to lift them so that is why I don't. Mine are in a sheltered spot though so that could be why it is ok.