STRIPE does support changing existing subscription pricing
Changing subscriptions
Stripe supports changing existing subscriptions without having to cancel and recreate them. Some of the most significant changes you might make are upgrading or downgrading the subscription price, canceling, or pausing an active subscription. Learn more about how to modify existing subscriptions in the Change subscriptions page.
https://stripe.com/docs/billing/subscriptions/overview#build-your-own-handling-for-recurring-charge-failures