Discovery is one of those things that you do from time to time via the Discovery Wizard (gear icon in Inventory). It is common to just need to run discovery, but not need to add more credentials or IP ranges, etc. I propose that a "Run Discovery Now" button should be added to Inventory in USM.
The button does 2 things.
1. Presents the list of discovery_agent locations.
2. Immediately runs discovery for that discovery_agent.
The idea is that you don't have to use the discovery wizard since you aren't adding any new discovery information, you just want discovery ran again since some device needs to be updated. A possible use case for this feature would be a new switch or router has been added to SNMP_collector or other probe, but It hasn't appeared correctly in USM yet. You click on the "Run Discovery Now" button and the new device now appears in Inventory.
I also propose that every discovery_agent probe in it's action list in Admin Console have a "Run Discovery Now" option. In Probe Utility for this probe there are the "discover_device" and "discover_now_and_schedule_next" options. Tie these PU functions to the "Run Discovery Now" option.