There is no way to change the Constitution.
Wait, I here you cry, there is a process by which a National referendum, with a majority (2/3rds?) vote can make changes.
Right, there is.
There is no way, currently defined, for a referendum to "come to the floor". There is no process by which John Q. Club-member can propose a referendum. It's undefined. Which leads to a multitude of possible interpretations... that it must be a Regional proposal, that it must be a District proposal, that only referenda proposed on the third Tuesday of every odd month can go forward...
Interesting, eh?
And yes, I've already mentioned this to the people working on the Constitution...
(Mind you, this is based on the latest version of the Constitution I have. I have already mentioned this, via e-mail to the developers working on this, so I assume that some steps are being made to put some sort of process in.)