I've seen multiple videos online of evacuation slide tests and they all tend to be almost violent as they are very fast and loud, but I can't help thinking that it must put a lot of force on those seams when they inflate and along with that the material. Is there any limit to how many times these may be deployed before they must be retired?
The slide has to be removed from the aircraft completely (generally) and sent back to it's manufacturer to be inspected and repacked, but yes, it can be reused.
As a far as "how many times", I would assume until it breaks ;). Though honestly, I doubt a slide would ever be deployed more than once, maybe twice in it's life span.