What are the main guidelines for reusing material from our own workshop papers in writing a new journal or conference articles? Is it generally accepted to republish own workshop papers again as a conference/journal article?
I agree with Heather. It seems to me that you can present your preliminary results on a poster, then extend it to a conference paper. The review process will give you nice hints to improve your research or writing in order to proceed to a journal article. It is not exactly the same content your are publishing, but as Heather put it, it must have significant new or revised content. And by the way, I would change the title as well.