Is there a way to preserve the VM configuration?
I'm afraid that you won't get a definitive answer for that. Re-Activation is triggered if Windows detects multiple changes, but I can't tell you exactly what it takes into account.
Anyway, a converted VM is basically a clone, which gets a new MAC address, and UUID. Assuming that you don't need the "old" VM anymore after the conversion, and that you didn't select opt to reconfigure the guest OS in the converter wizard, you could try as follows:
- convert the VM
- unregister both, the old, and the new VM from the inventory
- replace the new VM's .vmx, and .vmxf files with the old VM's files, adjusting the names, and any references to the names within these two files
- register the new VM again
- on the the first startup - if asked - answer the question on whether the VM has been moved, or copied with "I moved it". This will retain MAC, and UUID.
André