You can hire SEO expert to perform various activities like forum posting,link building,article submission and other.
Yes in a few case, auto approved blog comments harm our rankings. Avoid those blog where comments from pharmacy and porn sites are available. Always chose related and human approved comments blogs. By the way it is not too late. Start building quality links and you will gain your previous position.
Google change their Algo time to time. Sometimes new algo me devalue your links. So keep building quality links. You will able to reach top positions. Do not limit your link building to strategy to blog commenting. Use other methods also. You need to have natural link profile to get top ranking.
I have updated the content and its totally fresh and unique no doubt.its the offpage that is not working out.