Keeping the search string in the search box until done, with a 'clear search' option
Keep the wording of a search in the search box for ease of editing and reminding oneself of the search. Also suggest a 'Clear search' button for when done.
Alternatively, make the 'Edit search' option bigger, clearer and easier to find. It took me a while to even notice it was there, I had to keep typing out my searches again and again.