One often discussed point would be Italien neutrality. That would have tremendous reprecussions on the Russians as the Austrians can concentrate on them and the Serbians. Added to that, other minor powers will take note and the changing situation will compound.
What could the CP do for that? Maybe be a bit better in the Fall and Winter of 14 for the Austrians. Not impossible and even little, Imo, helps here.
Another diplomatic thing the CP could try, is a stronger pointing out of Entente actions, like cutting the cables and the blockade that was against the comon practice of the time and even against prior British custom.
That could rack up the pressure of the Entente and worsen their financial situation Imo. Also a strong point could be made of their culpability in helping on of the worst absolute monarchies of the time... namely Russia. So all the telling of fighting for Democracy and such will be so much harder.