S.L.
This is a tough one. My son ate so great when he was little, but now he doesn't like much. It drove me nuts. But one thing I refuse to do is make him something totally different for him. I probably get his favorite leftovers out of the fridge for him too much, though.
I have a friend whose son is 5, and he won't eat anything but hot dogs, chicken nuggets, and Kraft Macaroni. None of that is healthy! We sometimes have chicken nuggets or Kraft Macaroni, but it's not every third day, you know? How can he build a healthy body with fuel like that?
I don't have any magic answers except that you really probably don't need to worry about him eating every night. You'll get him into bad habits. And when he finally gets hungry enough, he'll try something you've made and just might find out that he likes it. My son, for example, discovered one night that spaghetti really does taste good! And those "green things" on his garlic bread aren't "yucky" after all.
One thing I've done is not get out his favorite part of dinner (the fruit, usually) until he's done trying some of the other stuff, or he'll eat all of the stuff he likes and decide he's not hungry enough to try anything knew.