The water tube for the indoor dispenser is leaking at the bottom of the freezer door and needs replaced. How do you do this without taking the whole door apart?

If the leak is right near where it enters the bottom of the door you may not have enough room to splice. I had a similar problem today when I crimped the hose while removing the door and sprung a leak

I just released the hose from the top of the water dispenser clips so it is free to move. I cut a new 1/4" line, inserted a small union inside the end of the old and new line to hold them together. I pulled the old line out through the bottom while feeding the new one from the top until the new line came out. Took a few minutes only.

Hope this helps. Not sure if your model is designed like mine . My model is GC5SHGXKTOO