My understanding is that if the sensors have worn to the point where the metal wire is exposed - then you they need to be replace them. If you don't want to replace sensors, just get a new set, plug them in, and zip tie them up. The computer will still show you how many miles are left - the sensors are so that the computer is given a different signal when there is a relatively small amount of pad material left. It will then switch to 200 miles left (or something like that).
Hope that helps.