I recently purchased a winch and a hitch mount for it so I can put it on either the front or back of my truck depending on which way I wanted to be pulled. I soon found out that the remote's cord was not long enough to reach into the cab of my truck while it was mounted on the rear hitch.
I did not want to purchase a wireless remote due to the fact that if the batteries die in it you're out of luck. I also did not want to buy an in-dash remote merely because of the price. What I decided to do was run into the local ACE Hardware and bought 15ft of the wire that has the three individual wires inside of the insulation (like extension cord wire) this cost me about $10.
I decided against merely buying an extension cord because I wanted it to look a little better so I got black wire to match. I was able to choose exactly how long I wanted it, and it was cheaper than buying an extension cord. I then cut my existing remote cord in half and spliced the three wires to the 15 ft section I bought at ACE.
Keep in mind, this method only works with the 3 pin remote plugs, I'm sure there is a way to do it with the 5 pin remotes, but I have a 3 pin. I also used shrink tubing to help secure the connections and I wrapped it up with electrical tape to no end. Good luck!