It would be appropriate to open the tongue for an excuse as follows:
O' Allah (the Glorious, the Exalted)! Through this noble month you did a great favour upon us and bestowed a great blessing, but alas, we did not appreciate it's worth, and by wasting this golden opportunity have oppressed our own selves, that you know about the dimensions of this calamity more than others. O' Allah (the Glorious, the Exalted)! Now that the Holy month has reached to the end and we would not longer have it's blessed days and nights at our disposal; the wind of Your blessings has blown towards us and awakened us from the deep sleep of ignorance; now we have realized that how much dearest one has been lost; with this loss, what terrible calamity we have inflicted upon our self; Now, we don't know any other way, except to look towards You; we admit our mistakes and wrongs which we have done to ourselves; that we have lost this great generosity feel sorry, that we have remained empty-handed from all those bounties shed tears with grief; now, who else is there except You, who could rescue us from this loss, and could treat this scare of intense grief from our hearts, and could lighten the burden of sins and regrets, which is so heavy upon our souls?
O' Allah (the Glorious, the Exalted)! In spite of our bad condition, wretchedness, deviations, and indecencies, we discovered that You have not forgotten and abandoned us to ourselves, has not released us in ignorance and negligence, and have not closed the doors of repentance upon us; otherwise, You wouldn't have made us aware of our mistakes and losses. Therefore, there is room, not to be disappointed from Your Generosity, not to turn off our eyes from Your blessings and bounties, not to remain empty-handed from Your Kindness, because, no one becomes hopeless from You except unbelievers, and no one except losers close their eyes from the threshold of Your Magnanimity.
Therefore, O' my Lord! You are so Exalted, Magnanimous an Acceptor that you accepted the magicians of Pharaoh's court, accepted his own prayer, and even did not return empty-handed, Satan, Your worst servant. For the sake of reverence of the Holy Prophet [s], please do accept me in this night, grant my prayers, change my wickedness into many fold goodness, delete my name from the list of losers and those who have suffered severe damages, by entering it in to the list of righteous and prosperous ones, and bestow upon me the companionship of Your most favourite saints.
O' my Lord! My sinning, deviations, indecencies, boldness, and immodesty have blackened my face; for the sake of the illumination of the Holy Prophet [s], and his Holy Progeny Ahlul Bait [a], please look upon me with Your Generosity, and allow me to sit under the shadow of Your Blessing. O' my Lord! This is the month of Your feast, You Yourself don't like that a host should act miserly in treating his guests, even if this hospitality would result in a loss for the host. But O' Allah (the Glorious, the Exalted)! Whatever You increase in Your benevolence and hospitality (towards Your guests) You have bestowed it upon Your own domain and kingdom, but if You deprive me from Your hospitality I would be left out hungry while sitting upon Your tablecloth.
Yes! It is up to such a person to see off this month through performing a perfect repentance with truth and sincerity, keeping in mind never to repeat the sinning, deviations, and transgressions committed by him in the past.