Its your flight instructor certificate that expires...not the ratings. If you're expired, you require reinstatement. If you're flying Part 121 or 135, this can sometimes be done in conjunction with the recurrency if those performing the recurrency are authorized. Otherwise, you'll need a new checkride with the feds.
Rather than take a checkride for an existing rating on your instructor certificate, you can also add a rating, and reinstate the certificate and all other ratings at the same time. If you're going to pay the money, why not go that route? If, for example, you hold airplane and helicopter ratings as instructor, why not add a glider rating. You needn't take the ride in a helicopter or airplane. You can add the new rating, take the practical test, and your instructor certificate is thus reinstated with an additional rating...and your helicopter and airplane ratings are also restored.
If your'e going to spend the money anyway, why not? Just a thought. I've let mine lapse twice under varying circumstances, and went for reinstatement each time. Once I did it with a designated examiner by merely adding an additional rating, and once I did it on a 135 ride with the FAA...they reinstated it when conducting the practical at the same time as the 135 initial ride.