The influence of the transition from the excited state on the coherent transients of pump-probe measurements in a three-level system is discussed. A theoretical study related to a selective scheme of differential absorption pump-probe spectroscopy is performed in the framework of a full semiclassical description of the interaction of light and matter. It is demonstrated how the coherent part of the modified signal may be used for detection of the up-transition from the excited state. Annihilation processes characteristic of molecular aggregates at high pump intensities are taken into account.