If you have recently cancelled your Hotstar membership, you will need to wait till your current billing period ends, in order to restart your membership. You can find the billing period dates in your My Account page.
You can also restart your membership from the My Account page. Your billing date will get updated depending on when you restart your membership.
You will need to provide payment information again. You may choose to provide the same payment method or add a new one.
If your membership was bought on iTunes, go to iTunes and enable auto-renewal.