Facebook Access Token Auto Renew

I created a PHP script that will execute every half hour auto post to a Facebook Fan page wall, since Facebook has updated their API, the Access Token is automatic expired in 2 hours, I have to re-create and update the Access Token manual on my script every hour, so I need someone to help me figure out the solution for this script, solutions: - check Access Token and create new one automatically if it expired, - extend Access Token expiration to more longer life one of this solution will be ok. I will show you script after awarded the project