Like Denny has said, whether your systems efficiency goes up or down when going from fly sparging to batch sparging depends alot on the efficiency of your fly sparge lautering system. If that is ideal, your efficiency with batch sparging will be less. If it is poor, then your efficiency with batch sparging will be greater.
One of the main ways to increase the efficiency of a batch sparge system is to crush the grist finer (Denny's "Crush 'til yer scared"). However, your lautering system must be able to handle a finer crush without sticking. Each lautering system (false bottom, manifold, Bazooka, SS hose braid) probably has its own "sweet spot" for maximizing efficiency (if that's even desirable) and not sticking.
Or you can just add more grain
