Velcro strips and glue

Our TM is 3 years old. The velcro strips are no longer sticking to the walls in several places. Do we need to reglue and if so what kind of glue do you recommend we use. Do we need to replace the whole velcro strip with a new strip?
Has anyone else had a problem with their velcro strips not sticking?
We love our 2720 TM. The towing is great and so is the gas mileage!
Thanks for any help.
fcullum