All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Whoever performs a ritual bath and then some sperm discharges out of his private parts after having the bath, then his bath is Islamicly valid. He does not need to repeat the bath since the sperm is the same and it does not necessitates two baths, as mentioned clearly by many scholars. Moreover, according to the correct opinion of the Muslim Jurists the sperm is pure.
For more benefit, please refer to Fataawa 91755 and 81587.
Allaah Knows best.