Remove duplicate content and use proper on page seo to get ranking back on top 10 results.

Do article submission on your site i sure your site will be stay in Google top ten if you found new idea then i will visit this forum.

Maybe the problem is that you are not doing seo of your site regularly, maybe you do it from time to time. It's not good and can result in the above mentioned situation.

I've noticed that with a website I'm working with at the moment, a lot of my keywords went from not within the top 100 to the top 20 within a month or so of starting my off-page SEO campaign (backlinking). Recently, the keywords keep dropping and dropping and I'm too getting a bit worried.

I wonder if it's due to not having fresh content on the pages being put in more regularly. The content on the website is completely unique but I'm stuck at the moment as to what to add in or change to maybe suit Google and give the website a push further up again.

So anyway, for your problem, I'm wondering if it is because your website is static and doesn't get updated regularly? Try inserting some more text every day or so to keep your website fresh, I know I will be doing from now on.

Well update are for those people who are using illegal method of SEO those who are working fine and on daily basis should not be worried and action will go against copy content also so be careful when you use same content.

Always use Content Plagiarism checker to first check your content is original & build niche links with quality in mind . 10 good links would be better from 100 spam links .
. Quality always matter in Search Engine Optimization .

Always make or try to put quality, unique and fresh content on your site and also make sure there is no grammatical mistakes on your site content.