Does feeling lustful after performing ghusl, due to remembering a previous wet dream, necessitate the emission of semen or pre-ejaculate, especially with the possibility of the semen from the wet dream still being discharged?

If a woman experiences a discharge and she is certain that it is maniyy (seminal fluid), then ghusl (definition) (ritual bath) becomes obligatory. If she is certain that it is madhy (pre-seminal fluid), then she must purify whatever it has touched and perform wudu' (ablution). If she is doubtful about its nature, she has a choice and may assign to it the ruling of whichever she wishes of the two.