Possibility For Reccurability

Found a little tutorial on creating something which appears for a few seconds and then goes away again. This could be useful for implementing in my code as a way for the balls to explode and then go back down and resume. Though a thought I've had is what will they do at the end? Because if they just go back down and recommence movement then the ball will instantly hit back into the exploded ones around it...

Here's the code
http://www.openprocessing.org/sketch/76841