Another possible workaround (not the ideal way to do it by far, but if you can't go back to the original...) is to create a form box with a white background to cover the piece of text, make it read-only (and make sure it is set to Visible) and then duplicate it over all the pages. Obviously this would leave a white gap, so it depends where it is on the page.
The best thing, though, would be to do as horqua said, but then in the first PDF you can use the Replace Pages feature so that you don't lose all your bookmarks and links (though that would only work if the whole document hadn't repaginated because of the deleted text).
There may be other workarounds, but I'd need to see the document before I could suggest them.