As Troy stated, you cannot increase space of a VM that has active snapshots. All snapshots must be deleted. However you could clone the machine in the desired state, rename the old one, change IP, ect, then increase the space of the clone and make it the new master. Please note that this may affect applications/licensing that looks at hardware ID's or other services. I've done this many times in the past to migrate RDM's over to VMDKs and it works well.
Hope that helps!