Praise be to Allah.
Prayer has certain conditions, without which it is invalid. These conditions include purity (taharah), which means removing major and minor impurities. Minor impurities are removed by means of wudu. A person must be pure and have wudu for each prayer, as Allah says (interpretation of the meaning):
“O you who believe! When you intend to offer As-Salah (the prayer), wash your faces and your hands (forearms) up to the elbows, rub (by passing wet hands over) your heads, and (wash) your feet up to the ankles.” [Al-Maidah 5:6]
If a person still has wudu , and nothing has broken his wudu (the things that break wudu are anything that is passed from the front or back passage such as urine, stools, wind; sleeping; eating camel meat; etc.), then he does not have to repeat his wudu . It was reported that the Prophet (peace and blessings of Allah be upon him) prayed all five prayers with one wudu on the day when he conquered Makkah.
And Allah knows best.