The ILS20 and ILS30 measurement devices do not get re-certified. They get exchanged.
X-Rite and Epson state that the device is considered to be reliable and repeatable if it passes its internal calibration.
That internal calibration is based on the white plaque on the side of the Backing Plate.
Typically the ILS20 or 30 will last for the life of the printer that it was installed on and is part of the warranty.
If you would still like to recertify, Epson runs an exchange program.
Q. I have an out of warranty Spectroproofer that needs to be
re-calibrated, what is Epson's out of warranty re-calibration service
policy for this product?
A. Epson's out of warranty re-calibration service policy for the
Spectroproofer product is a billable whole unit exchange. To receive out
of warranty support or to exchange your ILS unit that needs
re-calibration please contact Epson at 562-276-1305. To obtain pricing
information please contact Epson.