I think the OP is saying that their chinchilla has not wore it's teeth in a couple weeks? How do you KNOW the chinchilla has not ground teeth down in weeks? Eating along wears teeth SOME? Is there a reason you're concerned about this?
Teeth grow 1-6mm a week, if the chin is eating its grinding its teeth. If the chin is being had fed a soft diet, after 4 weeks or so it may need a filing.
I think Op means the chin is not using the chew toys to wear down its teeth.
Maybe you could try giving new chew toys? And more varied types? Like offer pumice, and different types of wood. Maybe some cholla or lava triangles/ledges?