Even though your website or blog has moved up in rank this doesn't mean that you can just stop worrying about your SEO and ranking. There will always be another site right behind you that continues to work on their SEO, improve their site, add articles, and attract new visitors.
If you fail to work on your site and improve your SEO efforts your site will soon fail and you'll lose your rank in search engines. As a website owner, there is no slacking when it comes to improving your site design, adding content, and working on SEO and advertising. You will always need to worry about your site and how to improve the content to attract more site visitors. If you are using your site to earn money then there is no stopping any SEO efforts ever.