How have you been "paying into it"? By definition, HRAs are funded by the employer, so you're not really losing anything when it goes away.
If you know you're leaving the company soon and won't be using your reimbursement, I would see if it allows for reimbursement for things like contact solution, crutches, etc., that have a long shelf life and don't require you to go to a doctor to get a prescription for them. Buy, get reimbursed, then flip on Craigslist or Ebay, or just return them to the store. Restock your first aid supplies at home that you will potentially use over their expected shelf life. I wouldn't consider doing any of that until I knew I was about to leave, since you never know when a major medical event will occur.
In general, I wouldn't think it's worth the hassle, and it is sort of an ethical gray area. Just be happy that you didn't have any medical expenses to have the opportunity to max out the reimbursements.