The following is the old school / clean approach:
1. Backup the current IP info:
cd c:\temp
ipconfig /all > ipconfig.txt
2. Set the current adapter to DHCP and reboot (stops the IP from being cached in the regsitry)
3. Shutdown guest
4. Remove old vNIC; add new vNIC (Edit Settings)
5. Power on and configure IP
6. Check for ghost adapters - remediate as appropriate
7. If you disabled any app services for maint, set back to automatic and reboot