Repay in kind is a phrase that refers to the act of returning a favor or kindness that has been shown towards oneself. However, there are other words and phrases that can be used in its place. One alternative is "reciprocate," which also signifies the act of returning a gesture. Another possible synonym is "return the favor," which is self-explanatory. "Pay it back" or "give back" are similar in meaning, emphasizing the repayment of what has been given. Finally, "mirror someone's actions" can be used to describe the act of returning the same actions that were given to oneself, whether good or bad.