Is it obligatory to make up prayers missed due to ignorance of the necessity of ritual bathing (ghusl) after menstruation or seminal discharge, or due to not knowing about semen (mani), pre-seminal fluid (madhy), or masturbation? And is it forbidden to leave the making up of any prayer for a full day?

You must repent to Allah for any shortcomings in learning the rulings of Sharia (definition) and for making up the prayers that were performed without purification, because they are a debt upon your conscience, and Allah’s debt is more deserving of being fulfilled. The fatwa (definition) issued is that making them up immediately is obligatory, provided it does not harm one's body or livelihood; otherwise, there is a fear of sin. Some scholars are of the opinion that one should make up no less than two days' worth of prayers per day.