In early October, I noticed that the top-most leaves were beginning to turn red. About October 15th, I brought the plant into the house and set it in front of my dining room windows, which are a southern exposure. It lost a lot of leaves in the first week, and then it started to put out new leaves, which, within 2 weeks, had turned almost completely red.
According to my friend who has a degree in Horticulture from NCSU, I am the only person she knows who has poinsettias that bloom again - and I have done it twice! I have no idea why the poinsettias I have decide to bloom again, but they do.
Supposedly, you have to bring them into the house and set them in a dark closet for a while, and that "resets their internal clock" and then they can re-bloom, but mine seem to like the conditions in my home, so they do their thing for me.
In Costa Rica, I saw a poinsettia plant that was so large it looked like a tree. The main trunk was as large as my arm, and the plant was over 6 feet tall. If I can find the photo of it, I will post it soon. Have you ever had a poinsettia plant that bloomed the second year?
You know that I am, like Hoss, always trying to "make my pile". I think I'll hire out as a poinsettia re-bloomer. You can bring all your left-over poinsettias to me and I will bring them back to you next December, blooming their little hearts out! How much would you be willing to pay for that??