Requirement here is to re-sit the exam and pass it. This requirement considers updates and changes of standards IEC 61508 and IEC 61511 and others and takes defined requirements of IEC 61508, chapter 6.2.13 into account:
(Procedures shall be developed to ensure that all persons with responsibilities defined in accordance with 6.2.1 and 6.2.3 (i.e. including all persons involved in any overall, E/E/PE system or software lifecycle activity, including activities for verification, management of functional safety and functional safety assessment), shall have the appropriate competence (i.e. training, technical knowledge, experience and qualifications)relevant to the specific duties that they have to perform. Such procedures shall include requirements for the refreshing, updating and continued assessment of competence)
However, it is highly recommended to refollow the complete 3 days training before re-sit the exam, as for some engineers after 10 years the fundamentals of the Functional Safety standard may be still clear, but the technical details and differences within the edition 2.0 of both the IEC61508 and the IEC61511 may be challenging to pass the exam without proper preparation as the complete training will offer you!