Set the ball down on a flat surface. Press one hand on top of the ball so it does not move when you are cleaning it; wipe the ball down with a clean rag. Move the rag over the entire surface and remove all visible dirt and other debris.
Add dish soap and water to the rag and press the rag into the grooves along the basketball. These tough-to-reach places can be filled with dirt and other debris, so they must be cleaned thoroughly to help restore the grip on the basketball.
Pour leather cleaner onto a new rag and wipe it carefully on the surface of the basketball. Move the rag back and forth in a circular motion until the entire area has been covered with the cleaner. This cleaner will get rid of the grease and other grime that dish soap and water could not.
Dry off the leather basketball thoroughly with a clean rag. Run the rag over the basketball until all the leather cleaner has been removed from the surface. Grip the basketball with either hand and check to see that the original grip has been restored.