Synonyms for Repay (same or very similar meaning)
WordNet sense 1 (act or give recompense in recognition of someone's behavior or actions):
reward, pay backWordNet sense 2 (make repayment for or return something):
requiteWordNet sense 3 (pay back):
refund, return, refundWordNet sense 4 (answer back):
rejoin, retort, riposte, come backFrom the ODE community, based on WordNetadd/edit