What should one who suffers from frequent forgetfulness and urinary incontinence do if, during prayer, he remembers that he did not perform ablution or remove impurity, and what is the ruling on past prayers performed in that state?

If you are certain that you prayed without ablution (wudu'), you must repeat the prayer. Similarly, if you realize this during the prayer, you must break it, perform ablution, and then resume it. If you are certain that you are afflicted with impurity (najāsa) during the prayer, remove it if possible; otherwise, break the prayer and remove it. However, if you remember the impurity after the prayer, you are not required to repeat it, because avoiding impurity is a condition only when there is knowledge and ability. You must make up the prayers that you are certain are incumbent upon you.