Replacement parts are extra, individual parts of an outfit or accessory set that are offered by American Girl.
Reasons to Order
It is quite possible that smaller parts can be lost or more easily damaged parts of a set will be broken or ruined. Rather than having to repurchase the entire item for one piece lost, a collector or parent can purchase the lost part individually.
Some collectors may only want one or two specific parts of an outfit, and so order just the replacement parts.
Sometimes, when items are retired, the parts will remain afterwards and thus can be ordered. This is not always cheaper than purchasing the item as a complete set.
American Girl's Policy
Over the years, American Girl has been fairly willing to sell replacement parts when asked about them. This can vary depending upon the individual customer service representatives. It has recently been reported by individuals that American Girl has recently implemented a policy where purchasing replacement parts for items that are part of the Girls of the Year line will only be available to those who can show prior purchasing of the original item. This is most likely to prevent overpurchasing of items that are in limited quantities.