Must I repeat my Maghrib and Isha prayers if I remember after performing them that I emitted madhy?

The madhy (pre-seminal fluid) is impure. Its emission necessitates washing the male organ and performing ablution, as narrated by the Two Sheikhs from the Hadith of Ali ibn Abi Talib, may Allah be pleased with him: "I was a man who frequently emitted madhy, so I asked a man to inquire of the Prophet, peace and blessings be upon him, due to the position of his daughter. So he asked, and he [the Prophet] said: 'Perform ablution and wash your male organ.'" Therefore, every prayer performed before washing the male organ and performing ablution must be repeated.