How to make the ball come back the way it came?

Question

I managed to get this first try surprisingly, but the ball won't come back. It travels up a line, when it reaches the top it should come back down but it doesn't. How do I do this?
https://code.sololearn.com/W3WMRFfe89By/?ref=app

Answer 1

Mirielle Thabks for the help, I'll do my best to understand it.