Șerban

On every single post, older than 1 year (365 days), you may add a custom formatted text, in order to let your readers 
know the information included might be outdated.

Old Post Warning

This plugin will display a custom notification on every single post older than 1 year (365 days).

Marios Alexandrou

** WARNING: DON’T USE THIS PLUGIN IF YOUR PERMALINKS INCLUDE DATES **
The Republish Old Posts plugin helps revive old posts by resetting the publish date to the current date. This will push old posts to your front page, the top of archive pages, and back into RSS feeds. Ideal for sites with a large repository of evergreen content.
Why would you want to do this? Here are a few reasons:
<ol>
<li>New visitors to your site haven’t seen your old content. This will help them discover it.</li>
<li>Old content won’t show up in date-based searches on search engines, but resetting the date can make them look fresh again.</li>
<li>People like to share and link to new content and they determine that by looking at the publication date.</li>
</ol>
A <a href="https://infolific.com/technology/software-worth-using/republish-old-posts-for-wordpress/#pro-version" rel="nofollow ugc">pro version</a> (a lifetime license is less than $15) with many additional options (see screenshots) for controlling when and what posts are republished.

Republish Old Posts

its not working with 4.6.1
nothing happens

not working please update

I love this plugin!

Republish old posts automatically by resetting the date to the current date. Promote old posts to users that haven't seen them.

Old Post Warning vs Republish Old Posts