Trouble getting correct count to show up at the right time

I’m trying to make a space invaders game to teach angles. Here’s the activity:

and here’s a tweet with an animated gif of it:

Currently, after the player has successfully blasted a space invader, they need to click on some text in order to increment the score and bring out the next invader. That’s a bit clunky. I’d prefer to have this happen without needing any user-click, but my attempts to use the clicker to do this have not worked yet.

Any help greatly appreciated!

Raj