Since the volume of a sphere is directly proportional to its diameter cubed, the ratio of the volume of the ball with a diameter of 4 cm to the volume of the ball with a diameter of 3 cm is $ (4/3)^3 = 64/27 $. Since all of the rubber bands have the same volume, it follows that the number of rubber bands in the ball with diameter 4 is \[ (4/3)^3 \cdot 54 = \frac{64}{27} \cdot 54 = 64 \cdot 2 = 128.\]Therefore the number of rubber bands that Alana needs to add to the ball is $ 128 - 54 = \boxed{74} $.