Editing every day is a bad idea, but editing occasionally to improve your gig is a good idea. Apparently the gig may take up to 48 hours to refresh into the search engine, but once it’s done that, if you’ve improved the gig as far as Fiverr’s unknown search algorithm of the day is concerned, it will go up. If you haven’t, it will go down. Having said that search ranking is random as far as I can see and you won’t know if your gig has moved as a result of your editing or something else.