Jackpot Replay is activated by making a purchase for one of the tiers. It's important to note that each tier of the Jackpot Replay has a limit on the prize amount that can be repaid, and successive purchases do not contribute to moving up in the tiers.
Only the highest value package has no limit on the amount which will be repaid.
When the Jackpot Replay is active, your highest qualifying Jackpot amount is recorded - Only Jackpot wins during regular base game contribute towards the event, not freespins, cash respins, or bonus game wins.