Hello Thumper,
No, unfortunately, you can not just change the SSID.
In this case is recommended to create again the SSID.
This will not change any values configured for the interfaces.
Just make sure that while you create the SSID, that it have the same configuration than the other one.
Once you do this, you can go a head and delete the first one.
Feel free to contact me if you need help doing this.
dmantill@cisco.com
Cisco TAC engineer.