Must one change underwear and repeat the prayer and the recitation of the Qur’an upon finding water of unknown origin after retaining urine with the intention of preserving ablution?

If you doubt the emission of water or it is probable that it is sweat, then do not pay attention to it, and your prayers are valid. However, if you are certain that it exited from the anus, then it nullifies ablution and necessitates washing the area touched by the impurity, but it does not necessitate changing clothes. If water exits and you do not know the time of its exit, then its exit is estimated to be after the prayer, so you are not required to repeat it. But if you are certain that it exited before the prayer, then you must repeat that prayer. You are not required to repeat what you recited from the Qur'an in any case.