The yeast is still alive :)
I keep adding sugar each night, and also a little ginger. It took about 20 minutes to start bubbling again tonight - I the yeast had died. In fact, I was about to dump it out, but came back to the computer to search for a more conclusive way to test it, and for a better way to start the next batch... it was only when I went back to actually dump it that I heard that characteristic bubbling like a freshly opened can of coke.
For a week that started out so badly, this week has potential after all.