No need to re-wire the trailer, unless you want to.
All you need is a new plug end. Its not a big deal. I broke one at the launch yesterday, came home and put a new one on in a matter of minutes. I seem to go through one a season. They don't last all that long if you use them a lot.
If your lights are giving you trouble, or the wires are corroded, then I would consider re-wiring the whole trailer.
They also have magnetic lights that work well.
Sinker