Code modification to CHANGE subscription price

[movielist]

Currently if you want to change the price of a subscription, everyone who is currently registered must be cancelled and re-register.

I would like to be able to change the subscription price, and keep the current subscribers until they expire.

The easiest way I can think to do this, is to keep, but no longer display the old subscriptions and make a new (selectable) one for the new price.

This way, when the current subscription expires, a user will have to renew with the new one.
And recurring-subscriptions would still pay the same, old price until they cancel.