Yes, you can! Here's how....Click the Add more link at the bottom right side of the IP Address Range to Explore. This will open up a window for you to add up to 3 IP subnets. (see screen shots below) Active Advisor's scanner will then attempt to scan these by order.
You can always perform multiple scans to get all of your subnets into Active Advisor. This may also be necessary when you physically need to connect to different subnets, or VPN into them. It is also always safe to re-scan a previously scanned network, in order to update devices or add new ones.
Additionally, you can also scan .0 or .255 addresses specifically by supplying them as single addresses with no ending address range, as shown above.