On your census Comments section, you can indicate your support for reinstating the mandatory long form. For example, "We would be happy to fill out a mandatory Long Form, to improve planning of public services". Statistics Canada can compile the comments and use these in future political arguments for reinstatement.
(Note that making this comment has nothing to do with whether you will be randomly selected for the voluntary National Household Survey.)
Spread the word! Blog, tweet, Facebook: Ask for the long form census!