Under the Style menu, there is an entry called DisplayFormulaNumbered. It does exactly what it seems to suggest: it indexes the contents of the cell by an auto-incrementing number. The numbering is updated throughout the notebook automatically. For instance, if I have three formulas numbered (1), (2) and (3), and I delete (2), Formula (3) automatically becomes Formula (2).
But the references to Formula (3) in the text of the notebook are not updated automatically. I have to manually change all of them.
Is there a way to automate this task? (Sorry, I can't seem to give a better description of the problem.)