When finishing checkin, the user must manually clear the search bar in order to start the new search. It would be a nice speed boost to not have to do this (even if there's a keyboard shortcut "Escape").
The potential downside is when checking in multiple attendees at a time with the same search parameters (i.e. a family), this might not be desirable. As a workaround, I would suggest preventing search results from refreshing in this case until keyboard input is received in the search box, in case prior results were still needed.