The LCD does not need to be 'refreshed'. Any information that you send to it will remain there until it is overwritten.
You generally only send information to the display in loop() if that information is changing, such as periodically updating a clock.
If you want to see if you can successfully display anything on the display you will have to do this in setup(). You should go back and try sending some information to the display in setup() and get that part working before you try to do anything with loop().
Don
[Edit]: Did you look at the Arduino 'kickstart' example that was referred to in Reply #1? Did you notice that loop() has nothing in it?