I often draw/design in SketchUp and then export to AutoCAD to produce working drawings. Of course, in SketchUp every intersection makes a new line segment and these end up in the exported DWG or DXF files. I used to clean up the CAD files manually in an older version of AutoCAD LT 2008 but have since upgraded to AutoCAD LT 2014.
I found a great command in this AutoCAD version called OVERKILL. Select linework and OVERKILL consolidates individual segments into long single lines - much faster than the manual method! I don’t know when OVERKILL was added to AutoCAD, but it be available in versions earlier than 2014.
I hope this is useful to others who use SketchUp and AutoCAD together. Cheers!