PDF editing apps such as Adobe Acrobat or PDF Pen pro can edit textual content, but they will not reformat the document ie.changing margins, page length, repagination, renumbering lists, etc. There really is not a good way to do that short of going back to the original document and application before it was converted into PDF. There are converters that are supposed to convert PDF into Microsoft Word format which you could then edit in Word, Pages, NeoOffice/LibreOffice/OpenOffice, or some other editor that handles Word documents. However the few times I have attempted to convert PDF to Word using Adobe Acrobat, the results were pretty dismal unless the document was dead simple and even then any automatic formatting such as page numbering was lost.
Later versions of Acrobat may be better, I haven't tried converting PDF to Word in a good while and I don't have a current version of Adobe Acrobat.
