Illustrator can make edits to your pdf one page at a time. Other than that you should get the native document make the changes there and make a new pdf.
If you have the coin, using Enfocus PitStop Pro is the best way to do a myriad of edits on PDFs, both single- and multi-page.
You can edit not only text, but do a heckuva job preflighting, editing, trapping and the like from a prepress perspective. Want to change color mode of an image? This will do it..
It's a plug-in for Acrobat, so you'll need the full version, plus an extra $600 or so for the plug-in. Pricey, yes, but well worth it.
