When macerating apples to use in a pie, what should you do with the liquid? Because the liquid is so full of apple flavor, I usually cook it down into a caramel and put it into the pie filling.   

I'm not sure this is good or even if I should be macerating my apples at all.   I originally started macerating to stop the pie filling from sinking, leaving a space in between the filling and my top crust.   Is there a better way to accomplish this?
On Serious Eats, Kenji Alt recommends precooking your apples (by a quick microwave or hot water bath) to set the pectin and prevent shrinking:

http://sweets.seriouseats.com/2011/10/the-food-labs-apple-pie-part-2-how-to-make-perfect-apple-pie-filling.html

Kenji is my favorite active practical food scientist, and a former recipe developer for Cooks Illustrated.