I created a cube in blender and exported it as RAW. Then I subsurfaced the cube, and again I exported it as RAW. I noticed the files were identical, so apparently the subsurfacing isn't getting saved. Anyone know how to save subsurfacing in RAW format?

When you subsurf the cube, make sure the cube is selected and press Alt+C and select "Convert to Mesh." The subsurfing will now be an actual part of the cube, as in points. All that's left is to export to RAW.