1Gb VE - Advice on license keys

Hi, our 1Gb legacy virtual editions went end of technical support on Aug 23rd - Because of this, we decided to upgrade our 1Gb VE's to new 1Gb VE's which hopefully will not be expiring any time soon.

We now have two new VE license keys to install.

As the current 1Gb VE's are in production, I was wondering if somebody can advise which option is best...

1. Create two new VM's using the two new license keys (This will be hard for us as the downtime will be significant - We will need to use the same IP Addresses).
2. Overwrite the existing license keys? Is this possible?

Anybodys help would be much appreciated.

Thanks.