Imam repeating some verses that speak of mercy or punishment

I do not know of anything wrong with that, because it
encourages the people to ponder and focus and benefit. It was narrated that
the Prophet (peace and blessings of Allaah be upon him) repeated the
verse (interpretation of the meaning): “If You punish them, they are Your
slaves, and if You forgive them, verily, You, only You, are the All‑Mighty,
the All‑Wise” [al-Maa’idah 5:118] several times.  

To sum up: if it is done for a good reason and not for the
purpose of showing off, then there is nothing wrong with it, but if he
thinks that repeating it may annoy them or result in disturbing sounds such
as weeping, then it is better not to do that, so that there will not be any
distraction. But if repeating it will only lead to pondering and proper
focus on the prayer, then it is all good. End quote.