I recently replaced the battery in my original remote ('98 has the battery holder clip attached to the case, probably why it still works 14 years later, lol!) To resynchronize it I stand behind the car, aim the remote at the center of the dash, press and hold the lock and unlock buttons at the same time until the lights flash/horn sounds, which is about seven seconds. Done!

To program a new remote: ProgramYourRemote.com