The only why to do this would be to create a new port, associated with the new IP you want. Then delete the port from your vm, and then attach the new port. This will cause the new NIC to increment by one in the OS as it will have a different MAC and the udev rules will make it increment.
The other option is to take note of the MAC address then remove the port and create and add it back.
To remove a nic from the VM.
$ nova interface-detach <server> <port-id>
$ neutron port-delete <port-id>
Create the port
$ neutron port-create [--mac-address MAC_ADDRESS] [--fixed-ip subnet_id=SUBNET,ip_address=IP_ADDR]
Attach the port
$ nova interface-attach --port-id <port_UUID> <server>
I will do it by editing network config and with static IP. If you are using DHCP then it will be tough.
I used DHCP.