In Renewal Settings, click the amount next to Rate to Charge for Plan (Fees Excluded), type the new rate and save. Every future renewal charges this rate (delivery fees, bag fees and tax are added on top as usual). The change does not affect orders already placed. If the subscription has a recurring coupon applied, the field is locked: "This subscription has the recurring coupon "CODE". Remove the coupon before changing the rate, then re-apply it." – because the coupon discount is baked into the rate.