I haven't seen anyway to monitor a device changing it's IP. SolarWinds uses IP for it's correlation and DNS to resolve the FQDN (Fully Qualified Domain Name) if there is one.
If they implement an ability to track by MAC address, so that it's doesn't change I could see this being done, and on the next poll the IP address could be updated like you are requesting, but this would also require a new way to monitor/poll a device since SNMP and ICMP don't operate at Layer 2.
Like stated above the problem is that SNMP and ICMP that is used to monitor/poll this equipment is a Layer 3 protocol and uses TCP/IP protocol suite to interface with the other protocols. MAC addressing is a Layer 2 protocol and can't route past a devices known MAC address table.. Once a device isn't located via MAC at Layer 2 it's assumed to be in a different location and the packet is pushed to Layer 3 for routing via IP address.
In short I don't see a way for you to dynamically keep this device updated with it's changing IP address in NPM.
Very nice! Forgot about this.
But, not hard for me to overlook I guess. I have ONLY monitored static IP's being mostly in ISP environments, and Enterprise LAN's where we aren't using SW to track Users that acquire DHCP..
Sorry for the mis-information about DHCP.. I would like to know or look up what NPM attaches to in the packet payload to poll SNMP and keep the IP updated..