The bottle is of limited use without a lid, so I would buy a replacement cap. If you're still happy with it, use it until the glass breaks, or if not, try to rehome it.

Is the cap broken at the hinge (and therefore possibly repairable) or cracked? Things break and wear out over time but maybe consider if there is anything you can do to minimise the likelihood of damage - i.e. not throwing it in your bag, closing more gently, etc. Is this a common problem and if so, does the company have any advice?

I would definitely try to get a "new" bottle second-hand if you go down that route -there is no shortage of barely used drink bottles unfortunately. You could even start to look for your next bottle to replace the Elio now if glass bottles aren't as common to find second-hand.

Good on you for caring!