There is a rumor that a Gamestop manager has stated that Gamestop will be having a better upgrade incentive for those trading in the original 3DS for a 3DS XL. Plus, the manager supposedly said that they will allow you to transfer your data from your 3DS to your new 3DS XL in the store so you don’t lose anything. We will just have to wait until Gamestop officially announces something about such a deal.
Source: gonintendo.com