Hi !
I've been making fabric hearts this year )
I too have only recently branched out from stuffing with dried lavender mixed with rice, so can't say that this definitely works long term yet, but I've started using natural wool stuffing, for stuffed toys etc. then dropping a few drops of EO into it before sewing up the final edge.
I also read on a pot pourri supply website that Orris Root Powder acts as a fixative for scents, so I'm going to try to get hold of some to see if dusting with a spot of that will help to keep the yummy smells for longer.
Please let me know if you try something and it works really well - I've not made any recently, but will get back to it as Christmas approaches!
Lisa x