Yes. Once you start using an IP PIN, you always have to use one.
If you are due to get an IRS IP PIN (Identity Protection PIN), the IRS is supposed to be mailing them in December and January. The current partial government shutdown can affect the IRS, however, so there could be a delay with the letters. Even last year, if I remember correctly, some IP PIN letters were a bit late.
Also see the IRS page below if you didn't receive or lost yours. There is a link to the Get an IP PIN tool to retrieve one, and there is also a special IRS phone number on the page for assistance.
https://www.irs.gov/identity-theft-fraud-scams/retrieve-your-ip-pin