Do I replenish the custom soil annually in the same quantities? The web site said you could use the custom made soil over and over. And how do I fertilize the second year?

Yes you can use the same soil materials over and over, just replenish it as it subsides in the box.

Fertilize each year the same, but don’t dig everything out of the box, in order to put the materials at the bottom the way you did the first year. And don’t worry if you disturb the Pre-Plant at the bottom of the box when mixing the materials. It is just to assist the soil underneath the box.