You will have to renew rather than revalidate your rating, which means that you will have to attend an ATO and obtain an assessment of refresher training required, if any, and a course completion certificate before finding an examiner to conduct a class rating proficiency check. If the rating has expired by more than 3 but less than 12 months, the ATO is likely to require you to complete at least two 'training sessions'.
The UK also permits Registered Facilities to provide refresher training for SEP class rating renewal although other states may not.