Q: After having bath (ghusl), sometimes semen releases after about 2-3 mins. Do I have to so the ghusl again?
A. After ejaculation, do not take a bath before one of the three points mentioned below is done:
a) Sleeping for a while.
b) Walking at least forty steps.
If one of the three was done and then a person took a bath and thereafter there was a release of semen, it will not be necessary to repeat the bath but Wudhu will break. Washing the area and changing or washing the soiled clothes will suffice.
On the other hand, if a person took a bath immediately after ejaculation without doing one of the three things mentioned above and thereafter there was release of semen, the bath will have to be repeated. (Raddul Muhtaar V1 P456).