[jimrod]

I racked my lager off the yeast 3 weeks ago by using co2 pressure to push the beer into the kegs. The old yeast has been sitting at 50* in my lagering fridge under 2# co2 pressure. It hasn't been exposed to air.
Is it still viable to re use?

[denny]

I racked my lager off the yeast 3 weeks ago by using co2 pressure to push the beer into the kegs. The old yeast has been sitting at 50* in my lagering fridge under 2# co2 pressure. It hasn't been exposed to air.
Is it still viable to re use?

Yep.