Feeding a pull wire (I use mig wire, but a coat hanger or even bailing wire will work if its long enough) from the top towards the bottom, hook and tape the new wire to the pull wire, and slowly pull it up through.

If your old wiring is still there, its much easier to tape the new wire to the old wire and pull the new up into place as you remove the old wire. In either case, you need to pull slowly and easily. The only attachment you have is the tapped joint. If it pulls apart, you get to start over.

The next option is to pull the headliner and replace the wire. Gene