how do you fix a wooden bat that has a crack an inch long and a pencil lead deep?
without throwing it away!

Hey, I've repaired my own wooden bats and they work awesome. Don't get suckered into paying big bucks to get it repaired from someone else. All you need to do is liberally apply wood glue to the open area and clamp down the separated part firmly. Let it dry fully and sand the excess stuff away. Then take it out and bat.
If you want to make the bat stronger, you can dip fiberglass cloth into fiberglass resin and wrap that around the middle of the bat, which is the most likely to break. It will take about 10 hours to harden but It is great once it's done. It hardly adds any weight to the bat either. You can get all this stuff at a Home Depot or Lowes, basically any home improvement store.