To fix a prelit Christmas tree, you can try the following steps: First, check the lights to see if any are burned out or loose. If you find any damaged lights, remove them from the circuit and replace them with new ones. If you're still having problems with the lights, it could be due to a faulty fuse or wire connection. In this case, you may need to check the wiring for any damage or short circuits. If you're unable to resolve the issue, you may need to call a professional for assistance.