Is it necessary to perform ghusl again if semen is discharged after having performed ghusl for janabah?

The jurists differed on the obligation of ghusl if semen exits after performing ghusl. The correct view is that if it exits without desire (shahwa), then ghusl is not obligatory, because it is a remnant of the first semen. However, if it exits with desire, ghusl becomes obligatory because it is new semen. This is supported by what was narrated from Ibn Abbas and Ali, may Allah be pleased with them both, that if something exits from a person in a state of janabah after ghusl, he should perform wudu. This is also because semen is one substance, thus necessitating one ghusl, and because it exited without desire. This opinion has been supported by Imam Ahmad, Sheikh Ibn Uthaymeen, and the Permanent Committee for Issuing Fatwas.