I just did the same thing by accident. Cancelled an Ink card before the AF came due by secure message but forgot to transfer the 350K + UR points to my other Chase Ink UR account. I called a few hours to explained what happened. A specialist came on the phone, reopened my account, transferred the UR points for me, then reclosed the account.

So yes, you can do this. The CSR was very helpful and polite to me.