If you upgrade at the time of renewal it is only $30 more plus tax rather than $60 if you upgrade at a later time.
What's nice about upgrading is then next year when you renew the Preferred annual pass, it is only $99 to renew which is the same price as to renew a Power Pass so you get more bang for your bucks. I always recommend upgrading a Power Pass at renewal time. You can renew anytime within the 30 day window of expiration---30 days before or 30 days after. Your expiration date will remain the same though no matter when you upgrade.