After getting some feedback about how the game played, I decided to make some changes to level 2. Here is what it looks like now.
The lasers will shoot in the middle of the top, and at the sides and will sometimes be below. What the celery is doing in a spaceship shaped like a banana is anyone's guess, and the fact that the blockers look like stalks of celery isn't exactly helping his cause, but I need them to be green because there is no color left. It's a lot like a Game Boy: You only get so many colors. In this case the colors are actual colors and not shades of gray, but there's only blue, green, red, and white to choose from. You can change the white to light green or light blue, but that change effects the entire screen, so you can't, say, draw a light green object and a white object on the screen at the same time.
Last night I got an idea for a third level. It's like the river part of "Frogger". Mr. Celery must hop on ice blocks and cross the screen five times in order to complete it. I made a background for it before I went to sleep and woke up this morning and changed level 2.
I added some evergreen trees just because I could. Work on this will begin tomorrow if all goes well with the level 2 changes.