Catalyzes the reduction of sulfopyruvate to (R)-sulfolactate. Together with SlcC, provides a racemase system that converts (2S)-3-sulfolactate to (2R)-3-sulfolactate, which is degraded further by (2R)-sulfolactate sulfo-lyase. (2R)-3-sulfolactate + NADP(+) = 3-sulfopyruvate + H(+) + NADPH Belongs to the LDH2/MDH2 oxidoreductase family.