If you are already a Platinum Elite player and would like to extend your validity, all you have to do is keep meeting with the criteria for qualification into Platinum Elite.
For Example: Let's say that you are upgraded to Platinum Elite on 15th May, 2019 and your status is valid till November, 2019. If on 10th June, 2019, you again have 16,000 Loyalty Points in your account that have been accumulated since 1st April, 2019, you will enjoy extended Platinum Elite validity till the end of December, 2019!