At least up to JDK 1.4.2 this isn't possible!
You have in all JDK versions the function jni_DestroyVM, but you can't
create a new instance of the JVM in the same process after calling this
If my memory serves me well, this should be possible with the
Java 5 JVM, but I haven't give it a try and, to be honest,
I doubt that it is really working in Java 5 until I have seen
it working on my machine ;-)