When there are no powers left to learn, no mountains left unclimbed and no monsters left unchallenged, it is time to be reborn.

What is Rebirth? Rebirth is like reincarnation. Your character is born again as whatever class and profession you like.
  However, memories from your character's previous life linger, granting you additional powers, skills and abilities from your old class.
  Reborn characters are much more powerful than newborns, with more potency, higher abilities, better skills and visual glamour.

When can I be reborn? Archers, trojans and warriors can be reborn after they reach level 120. But water taoists, who are more spiritually enlightened than others, can be reborn at level 110 -they have lead a more fulfilling life, and are ready to be reborn at a younger age.

Why be reborn? The best reason to be reborn is obvious -to play the game again! But you'll also be able to try out a host of interesting skills and abilities, available only to reborn characters.