Attic insulation problem?

I just found out I have only a 2" R-8 BAT in between my cieling trusses, no blown in insulation. The vapor barier is on the drywall side, and there are no ridge vents. Would it be easier to take all that insulation out, and install proper R-value, or add cellulose and ridge vents? since I have some insulation even though its only R-8 how much blown in should I build to? Thanks..David