Most people would want to change the key because of the damaged rubber pad on the remote.
There are people selling in the US ebay for about US$50 each uncut key with remote (add a few dollars for shipping). Send this to your trusted key cutter to have it cut, than open up and swap the electronic part.
This wouldn't cost a lot, would it?
Someone posted this programing instruction as below:
1) Get in and close all doors.
2) Turn on the ingition and turn off quickly. (No more than 5 seconds) to start the process. Next action must take place within 30 seconds.
3) Remove the 1st key.
4) Hold the key up near your left shoulder (this is so it is closer to the remote reciever antenna - someone else suggested this).
5) Hold down the unlock button (which is button 1 on my key) and press the lock button 3 times (center button on my key). Release the unlock button and the doors lock which confirms the operation.
6) Quickly repeat steps 4 & 5 for key #2 etc.
If it does not work, try doing the keys in opposite order. Key 2 then key1, vs 1 then 2.