This is extremely useful when you have run a Find but have then decided that you would like to change (re-specify) your search to look for slightly different items.
You can find the re-specify tool under the Query menu, so you click Query and choose Find. This will bring up the Find dialogue box which shows you existing search. To change them you click Re-specify and the Find dialogue box will show once again however this time you can change the search parameters. You can now amend the parameters that you would like to and run the revised search.