Well, when I took the photos above last Christmas, I managed to break off a new 10cm shoot (I think it is supposed to be stolon). I put this broken stick in a pot with soil. After a couple months, it became brown, so I assumed it was dead. Then I was repotting a month ago, and discovered this:
At the base (right top) of the broken piece, which was under the soil, there are 2 new growths (white things)! I repotted it into a new pot, and they are growing a little bit after a month.
Magnified view:
For the main plant, I managed to break off the 2 new growth points again during the repot.... Mmmm, this species is so fragile, but I'm sure that the broken pieces will grow. I added this info to the original blog post.