Caution here.....Jeep remotes are supposed to only work when you are around 4-5 metres from the vehicle, the remote also requires 'line of sight' to the sensor..its got nothing to do with the age of the remote.
This is a security feature aimed at not making life easy for car thiefs...if a set of keys is found with the Chrysler or Jeep insignia it would be a simple matter of pointing it in their general direction in the shopping centre carpark...many a Holden and Falcon have dissapeared this way!.
If yours is acting up its probably due to one of two things, batteries getting down, CR1616's x 2, about $5, or there could be an intermittent fault internally, really quite easy to fix, check out my website...
http://www.users.bigpond.com/pfgreig/