update

src/main/java/PingPong/GamePanel.java

@@ -83,6 +83,12 @@ public class GamePanel extends JPanel implements Runnable {
             newPaddle();
             newBall();
         }
+        if(score.player_1 == 20){
+            score.player_1 = 0;
+            score.player_2 = 0;
+            newPaddle();
+            newBall();
+        }
     }