Once you have met all the revalidation requirements, if you are talking about the UK then you must take your licence, logbook and Form SRG\1119 to an Examiner
within the last 3 months of the Rating validity period!
That is an unfortunate CAA error; JAR-FCL states that you can have your licence signed any time in the last 12 months for a further 24 months from the rating expiry date, but when the ANO was drafted, the CAA cocked-up and confused the 'last 3 months' applicable to revalidation by LPC with revalidation 'by experience'.....
You should not be charged anything for a simple signature in the licence by an Examiner; if you are, then name and shame!