Mistletoe is a parasitic plant. It develops root like structures that spread through the tree branch to which it is attached. If you cut off the mistletoe, it will resprout. However, there will be no mature mistletoe present to develop seeds, which is how mistletoe spreads to new branches. Removing the host branches is a better long-term solution, especially if you can cut the branches off at least 1 foot below where the mistletoe is growing. Keep in mind that most healthy trees can handle a light load of mistletoe. Mistletoe takes nutrients and moisture from its host tree, but trees often flourish for many decades with a few clumps of mistletoe growing on their branches.