From the link:
he article is based around the question of whether it's okay to "plagiarize yourself," but I worry that even that's a bit misleading. You can't plagiarize yourself. Plagiarism is about passing off someone else's work as your own. Reusing work is not the same thing at all, but is a separate issue -- and one that doesn't really seem to be much of a problem once you think about it.
You can use yourself all you want, just source/cite it.
Oh, and I allow some students to use previous works, IF they ask first and it meets the requirements for the paper (most all previous works do not and the student that re-submits a previous paper usually does worse than if he did independent research.