§ 61.199 Expired flight instructor certificates and ratings
(a) Flight instructor certificates. The holder of an expired flight instructor certificate may exchange that certificate for a new certificate with the same ratings by passing a practical test as prescribed in §61.183(h) of this part for one of the ratings listed on the expired flight instructor certificate.
(b) Flight instructor ratings. (1) A flight instructor rating or a limited flight instructor rating on a pilot certificate is no longer valid and may not be exchanged for a similar rating or a flight instructor certificate.
(2) The holder of a flight instructor rating or a limited flight instructor rating on a pilot certificate may be issued a flight instructor certificate with the current ratings, but only if the person passes the required knowledge and practical test prescribed in this subpart for the issuance of the current flight instructor certificate and rating.
[Doc. No. 25910, 62 FR 16298, Apr. 4, 1997, as amended by Amdt. 61–104, 63 FR 20289, Apr. 23, 1998]
If you can understand that, you should find your answer.....goodluck!
I always thought that you just retake the practical, but the section (2) has me confused. To answer to the second part of your question, you can only renew your CFI, by adding an additional rating, if your certificate has not expired. Check 61.197.
For all you guys considering getting your CFI, they are required to renewed every 24 calendar months. I would recommend reading Part 61 subpart H. There are a few different ways to update these but I would suggest American flyers. You pay $125 once and can renew every two years thereafter. For a little more they will take care of all the paperwork for you, which is nice if you don't have a FSDO nearby. I used this program while I was in UPT and it worked great. There are a few other companies out there that charge you that price every time you update. A Flight Instructor Refresher Course (FIRC) is another way to renew your CFI, but usually run around $150 and consists of two 8 hour days, and again that charge is every time you attend one.