Due to anti-spam laws, we can not re-subscribe you if you have unsubscribed.
You need to go to http://www.listbox.com/member
Once you are in, at the top of the page, you will see Subscription Status
Below that you will see an option to Rejoin now
Click on that option and you will receive an e-mail request to confirm your action.
Once you do, Clever Commute will re-add you (might take a day or two).
UPDATE: As of Spring 2015, we strongly encourage all users of the old e-mail-based way to migrate to the new, free app. See clevercommute.com/app for more info.