Pink lemon trees are a variation of the Eureka lemon and are even less hardy than the Eureka tree. All lemons are known for not being hardy to frost and freezing temperatures. If your tree has weathered some low temperatures, don't give up as there is a good chance that it will survive. There are some measures you can take to revive your tree but don't do anything until you are sure that it has frost damage.
Wait. Even though you might be sure that the frost has damaged your tree, you will not be sure how much damage occurred until you wait for the dead growth to show itself. Sometimes, this might mean waiting until spring if you are in the middle of winter. The exception would be in early fall when the fruit is still on the tree. You can pick the fruit and use it while you wait to see if the branches are hurt.
Allow frost-tipped leaves to continue to grow if the branches they are on are not damaged. You might notice some black-tipped edges on the variegated leaves, but it will not affect the fruit. If the leaf was truly killed by the frost it will fall off on its own.
Scrape away some of the bark on the branches where you suspect the tree has suffered damage. If enough time has passed, you will see the growing area as green and the dead area as brown. If large areas are dead, wait several weeks or months before pruning so you can give the tree enough time to grow some leaves and recover on its own before you remove the dead growth.
Cut away the dead part of the branch making a downward angled cut to keep rain from pooling on the cut. For deep freezes where the temperature stayed below freezing for several days, the part of the tree above ground may die while the rootstock could live. New leaves will emerge in the spring and if your tree was a graft on a wild rootstock, the resulting new growth will be the wild stock and not usually worth saving.