Is your blog rich with content you've written over the last several years that's still relevant and valuable?
Use social media to drive fresh eyes to those articles.
Set up a series of social media posts (Facebook, Twitter, LinkedIn, and whatever other platforms your target market uses) with brief snippets of information and a link to those older blogs. Encourage readers to follow the link to read the old blog posts and join in the conversation.
Consider making this a regular type of social media message, maybe with a tag such as Worth Repeating or Flashback. Just be sure the article is not outdated and the information is still useful.