Why does a tennis ball bounce higher on a smooth surface?

It only bounces higher when you are speaking of the ball being hit or thrown over a distance - that is, at an angle to the hill. Under this condition the Force that has propelled it both forward and downward is exhibited as both a horizintal and a vertical force.

The reason that it bounces higher under this condition of 'meeting' a slope is because the Force that has propelled it in the forward direction is arrested somewhat - such that that aspect of the overall force is converted into a vertical plane, so that now the kinetics comprise those invloved in the original 2 directions all compunded into an upward direction.