We explore the effect of on and off-center repulsive impurities on regular parabolic dots and their impact on the level structures coupled with a variation in the dot size. Information entropy and probability density are invoked to monitor the pattern of evolution of the electronic states. We have considered Gaussian impurity centers of repulsive type. We have found that the dot size and impurity position interplay in a subtle way to modulate the spatial arrangement of impurity doped dot energy levels. The information entropy profile evinces emergence of resonance-like situations and the probability contour delineates the alteration in the spatial extension of the system for different dot sizes and impurity locations.