It is possible to convert PDF files that contain CAD data for printing back in to DWG format for editing. Several CAD tools or even some converter utilities should be of help here, even some vector graphics software like Adobe Illustrator might be able to help you achieve pdf to dwg conversion, or at least some partial recovery.
Open PDF file Open DWG fileA 3D product data optimalization software
A software that converts PDF to DWG and PDF to DXF format
A professional architecture design software
A landscape graphics design software
A CAD CGM converter