to change the terms of a mortgage(= agreement by which you borrow money to buy property), usually by increasing the amount of it, in order to be able to borrow more money(尤指为了得到更多钱而)再抵押,转按揭
Robin decided to remortgage his house to pay off his debts.罗宾决定将他的房子进行再抵押来清偿债务。