No way you will make it from KLIA2 to KLIA in 1 hour. Just impossible.
KLIA2 is a totally different building. There is no sterile transit from KLIA2 -> KLIA. Also KLIA 2 is huge, and if you park at one of the far gates, you need 20mins to walk to immigration. Then clear immigration, collect bags, take the train (5min ride), 20min frequency, re-check in.
Without baggage, I would attempt it only if I have a minimum 2.5hrs. Any delay would make it challenging