To make your ping pong rubber sticky again, regularly clean it with water and a cloth, or mild soap for deeper cleaning, then cover it with a non-adhesive protective sheet to maintain tackiness. Occasionally apply a small amount of mineral or baby oil to restore stickiness, ensuring you leave it covered for a few days. Always store your paddle in a case to protect it from dust, dirt, and sunlight, and minimize direct hand contact with the rubber. If these methods don't work, consider replacing the rubber for optimal performance.