To restock your sold out accessories for free, click 'edit' and tap on the item which needs to be restocked, then select the 'box' option. This sends the accessory back into the 'shop' menu. Choose 'back' then click the 'shop' menu and go to 'accessory'. Here you will find your accessory with the label 'place' under it. Select the accessory and place it back into your store. The accessory is now completely restocked without decreasing your cash.