Forgot to Do Ghusl, Should I Repeat the Prayer?

As regards the question, there are two points to discuss. The first is your delaying of ghusl from Janabah (major ritual impurity), since this may obstruct you from offering Prayer in its time. So, a Muslim should hasten to do ghusl when required to be able to do various recommended deeds, such as reciting the Qur’an, salah, entering the mosque, etc.

As for the prayers you have performed during this time, while forgetting to do ghusl from janabah, the late sheikh Ibn Baz, a renowned Muslim scholar, stated,

If a person remembered that he had a wet dream and have ejaculated semen, then he must offer ghusl for janabah and repeat the prayers which he offered during the time between his wet dream and before doing ghusl.