All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
If the prayer’s time ends while the person suffering from urinary incontinence is performing the prayer, many scholars held that his ritual purity (Wudhoo') is invalidated. According to one of the opinions of the Shaafi‘i scholars, the person's prayer for which he purified himself is not invalidated even if its due time ends. The Maaliki scholars held that the ablution of the person suffering from urinary incontinence is not invalidated by the end of the prayer’s time.
In any case, when the prayer’s time ends while the person who suffers from urinary incontinence is performing it, he should complete his prayer, based on the view that his ritual purity is not invalidated by the end of the prayer’s time. However, if he makes up for that prayer later, it would be better and more prudent so as to be on the safe side and depart from the scholarly difference of opinion.
Allaah Knows best.