You can only contribute to an HSA if you have an HDHP. Once you have taken the money out to pay medical bills, there's no "do over" as far as I know. At this point your options are to leave the money in the account, roll it over to a new HSA, or use it to pay medical bills over the next few years. Given that you have fees if the account goes below $1,000, you may want to save up your medical bills until you have spent that much, get it all reimbursed at once, and close the account at that time. I personally don't think it's worthwhile to bother with rolling it over and investing such a small sum if you don't intend to have an HDHP in the foreseeable future that would allow you to contribute more.