You don't actually lose any anatomical length. Sometimes the additional filler (especially at the base) can pull or constrict (wish I can think of a better word) the skin, creating the appearance of lost length (often negligible, seldom significant).
The simple solution is to do mild manual stretching daily (perhaps while you're in the shower), and if you wish to expedite the process, look into pumping or a stretching device routine -- of course be sure to run this by your performing Physician first, but it tends to work like a charm for everyone who has experienced these issue(s).