I have an idea, but I'm not sure of the Linux command to do this, what you need to do is to release the ip address in omv (on windows machine it's ipconfig /release from the command line)
Then reset your static ip option on your router, shutdown and reboot the should assign that new static ip via the router, the following is from the manual.
According to that it will assign the ip to the Pi, but the current one needs to be released, what I found is dhcpclient -v -r from the command line, but to that you'll have to have a keyboard and monitor so you can shutdown shutdown -r now this will shutdown and reboot the Pi smoothly, rather than pulling the plug.