Are you saying that you are missing the laptop, but that you registered it with some company site based on the serial number, and when you go the site and search on the serial number it gives you the IP that the laptop is being used from?
If that's the case your company has some software already installed that is tracking where the laptop is being used from. You can do a whois on the IP address and get a general idea of what ISP it's being accessed from and a general location.