When should I replace the catalytic converter on my 2002 vw tdi beetle?

I want to know when I should replace the catalytic converter on my 2002 vw tdi beetle along with any other part of the exhaust system. It has 110,000 miles on it now?When should I replace the catalytic converter on my 2002 vw tdi beetle?
it is about that time to change it but not necessary until the car cuts off and fails to stay running.

you will notice the feeling of shaking while idling.in most cases it will fail to stay runningWhen should I replace the catalytic converter on my 2002 vw tdi beetle?
if no problems with the cat then its ok if problems then has to be done asapWhen should I replace the catalytic converter on my 2002 vw tdi beetle?
you don,t have to as long as it,s still good.
There is no time schedule for that to be replaced if it fails smog on certain max pollutions it could be a cat if you feel the need you can have it tested at shops usually a bad plugged cat or cats will result in hotter running engine overheating because it can't push out the hot gases and it builds to much back pressure also other symptoms is loss of power and hasitation when trying to start from a dead stop.