For the apple syrup, empty apple juice into a large saucepan (7-liter pot) and add the sugar. Stow the spices in a muslin bag and tie tightly. Add the bag to the juice as well.
Peel the lemon thinly and squeeze it. Also add to the pot. Boil the liquid for a good 10 minutes and then fish out the lemon zest and spice bag.
Bring to the boil again, bottle the apple syrup and use as desired.