PDF is not intended for this type of processing. It is a one way, to print protocol, and is proprietary. If you absolutely have to have the content in the PDF, then cut and paste it! that is the best for free advice I can give you.
As a business man, I always converted my documents into PDF, so that my customers could not take my document, and alter it for their own use, or to change bottom lines or such. So what you are attempting to do is really is trying to circumvent the security of the document, which is why it has been flattened into a PDF in the first place!