Yea, you have to stabilize the lucid regularly or it won't last long at all. Or get really involved in the story, I've had long lucids without stabilizing simply because it was such a wacky dream.

Also, short DILDs are the perfect time to DEILD. DEILDs are also really good for teaching you how to WILD, I highly recommend them. Whenever the dream fades don't lose focus, so when you wake up you won't move at all and you should be able to reenter the dream pretty quickly.