Re-entry means riding up the face of the wake, popping an ollie or another move off the lip and then landing back in the transition of the same wake you started from, like you would if you were riding a wave or a quarter-pipe.
http://wakeboardingmag.com/how-to/hi...le-re-entries/
http://wakeboardingmag.com/how-to/hi...le-re-entries/