You have mentioned in the question about a divorce in past. If your friend has given talaq in past then as much talaq he gave that much took place. But if he did not give any talaq in past then too one talaq rajai took place, as talaq takes place by admitting talaq in past. However, in this case your friend shall have the right to take her back within iddah period. And the method of raj’at (taking her back) is that he says that he has taken back his wife in front of two persons. Then it shall be right for them (husband and wife) to live together. If he did not take her back within iddah period then the woman shall become bayina (separated) and now it shall be necessary to do fresh nikah in order to take her back in nikah with the mutual consent of both parties. It should be noted that the iddah period of a woman experiencing menstruation is three haiz (three menstruation cycles).
Allah knows Best!
Darul Uloom Deoband