There’s no need to bring the temperature up again for dry hopping. Continue lagering the beer after dry hopping for several weeks, then keg or bottle the beer. The hops may cause some clouding of the beer, so a clear beer will have some turbidity get back into it. Dry hopping at lower temperatures works fine.
After lagering with the dry hops you can bottle or keg the beer in a couple of weeks. At cold temperatures the risk of vegetal flavors from the hops is low. If you bottle you will have to raise the beer to room temperature to condition it until it’s fully carb’d, you can then return it to near freezing temps for additional lagering if necessary and for storage. If you’re kegging, the beer can be kept at near freezing temperatures for additional lagering if needed and storage.
