You can give to her areal roses every special day you spend with her,, and she can keep it to remember all the good days you are have in your relationship...
A charm and each time you do something memorable you can buy her a charm to mark the occasion. I'm sure she will be able to find a bracelet to put it on and you will always have a gift idea. Let us know what you decide plz :)
Maybe you could bring her to a very nice and peaceful place, and give her a nice kiss.
I think you should give her a photo album and fill it with all the good memories you have had so far. :D as a girl/girlfriend I would absolutely loveeee to get this. It would deserve a kiss on the cheek. Hope it helps :)