Cut off the damaged tip and it will probably create 2 new branches in time.
You can even cut the tip off a bit further down into the live material. Then take the cutting (frag) and cut most of the dead part off. Put a drop of super glue on a frag plug or a small piece of rubble rock and stick the dead end in the glue. Even though it's now upside down, it should heal up and grow. It's not a plant, it's a colony of animals and they don't care from right side up or upside down.