Adding a second lease bar to your warping mill will allow you to have a cross at each end of your warp.
The way we generally use of this second lease bar in our studio is to wind only half of the width of a symmetrical warp with a lot of tedious color changes. The cross at the top of the mill belongs to one half of the warp, and the cross at the bottom of the mill belongs to the other half. This saves an a lot of time and tedium when winding any symmetrical warp that has multiple color changes. It is also a good way to use up odd bits of leftover colors: you can design directly on the warping mill, and have a symmetrical design.
When you chain off the warp such as this, chain from the top cross and down to the middle of the warp. Then start a new chain, and chain down to the bottom cross. The second section of the chain is ready for use, because you have the cross at the correct end. The first section needs to be re-chained in the opposite direction, so that you have a cross at the correct end of it as well.