SEO is NOT just set it and forget it.
The days when SEO was a set it and forget it practice are long gone. Today you need to constantly be updating your site and its content to not only boost but to maintain those rankings.
Search engines like Google are constantly surfing web sites to see if anything has changed. If it has changed ...and in a positive way with good content and key words then Google will boost up your rakings for those new keywords or even boost it up for ones that are already being found for.
Let’s say that you have a top competitor who ranks just below you in the rankings ...when your web site is crawled by search engines, If your content has not changed, but your top competitors content has, then they will jump ahead of you in the rankings and your web sites rankings will fall.
When your web site gets cashed in to a search engine, its rankings will constantly be shifting up or down for multiple factors, such as updated and newly added keyword rich content, inbound links, and competition rankings. So, remember it’s not just set it and forget it, update your web site often and not only keep but boost those search engine rankings!