First of all make sure that the cancelled RP's original expiry date is still alive? If yes, the procedure is easy. Secondly, how many months finished the cancellation date and date of journey? If both answer are less than 6 months then try to cancel the cancellation by the same sponsor. Ofcourse, final decision from immigration authotiries. If all are more than 6 months, then you have to complete all procedures as a new employee.