It is important to remember that being relevant online is not the result of an “event” or singular campaign, but a continual, ongoing effort.
Your site may be listed as one of the top search results right now, but that’s no guarantee it will stay there.
If your website isn’t being continually updated with new, fresh content, (eventually) the search engines will simply move on to sites with newer information. Ideally, this means you’ll have new content on your site every time the search engine crawler (an automated program used by search engine companies to review websites) visits.
This can be as simple as quickly updating an old post or page. Just make sure something is different. This shows that your site is being actively monitored and managed, which is obviously a good thing.
This ensures that the crawler will have fresh content to index and new links to explore. Thus, it will never see your site as stale and decide to drop it from the rankings.