The guest speaker at the February meeting of EAA Chapter 90 was a shop foreman in electronics for United Airlines in San Francisco. The main points he made concerning wireing our experimentals, that stuck in my mind, were to: 1- Use the proper ratcheting crimpers and terminals, 2- Use wire strippers with a stop guage, 3- Dont' use tie wraps to bundle wire runs. United and Boeing don't allow tie wraps, they eventualy cut throught he insulation and can cause shorts. Airbus does use tie wraps and United removes them and replaces them with tied lacing. 4- He said the wire runs in our airplanes are so short- don't splice wires, pull the old ones and replace with new wires. He said to use a "spoon', Stein carries them, to fish the new wires into a bundle.
My thoughts are, replace the wire if at all possible. If replacing the wire is not a realistic option, then a splice like Brian suggests, will of course work.