How to Refresh LinkedIn Access Token
Unlike other social media networks, LinkedIn does not issue "Long-lived" access tokens. Long-lived access tokens are tokens which last a very long time without a user needing to re-authorize a service.
LinkedIn access tokens however usually last 60 days. Once your token is almost due to expire, the Revive Old Posts plugin will send you an email (to the admin email inside Settings->General) as well as add a message to the plugin log area about the impending expiry.
All that is required on your part is to simply reconnect your LinkedIn account Revive Old Posts like you did the first time when adding it to the plugin:
Head to the Accounts area of Revive Old Posts and click on the LinkedIn network button:
If you have more than one account connected you'd need to click the Add more accounts button to show the network buttons:
Click the "Sign in to LinkedIn" button
After clicking the button a new window will open up asking you to sign in to your account. Proceed to sign in so you can give ROP access to sharing to your account
Once that's done you'll be all set and the plugin will notify you again when the token is due to expire the next time around.