The Jackpot Replay feature is activated by making a purchase for one of the tiers - each tier of the Jackpot Replay has a limit on the prize amount which can be repaid, and successive purchases do not contribute to moving up in the tiers (only by making the necessary purchase to activate a certain tier of the Jackpot Replay will do so).
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 gameplay contribute towards the event, not free spins; cash respins, or bonus game wins.