What is the ruling regarding the prayers I performed while in a state of major ritual impurity (janabah), first out of ignorance and then out of neglect, and do I have to repeat them, or should I instead increase in supererogatory prayers as a form of repentance?

If someone prays while in a state of major ritual impurity (junub), ignorant of the ruling regarding his action, his prayer is valid, and there is no sin upon him, nor is there a need to make up the prayers he performed, provided that he was not negligent in seeking knowledge and inquiring. However, if someone knew the religious ruling and prayed while in a state of major ritual impurity, he is sinful and must repent and make up those prayers. As for the congregants who prayed behind him, their prayers are valid, and they do not need to repeat them.