It should have a Refresh button at the lower right like all the other list views.
commit 8067be4a926ae924669cad9a7619882ac5d35c3d Author: Jay Shaughnessy <jshaughn> Date: Wed Apr 20 17:51:37 2011 -0400 [BZ 697581 - Discovery Queue view is missing a Refresh button] Added refresh button
Verified on build#28 (Version: 4.0.0-SNAPSHOT Build Number: da7bcb0) The Discovery Queue view has a Refresh button at the lower right on 'Inventory'->Discovery Queue' page. Clicking Refresh button refreshes the page. Also added a Discovery Queue portlet to the dashboard and verified the display of Refresh button. Marking as verified.
Bookkeeping - closing bug - fixed in recent release.