There might be subscriptions and invoices records linked to the plans and addons. So it is necessary to move all the plans and addons to PC 2.0, including the archived ones.
However, if there are no subscriptions attached to the plans and addons that you do not want to move to PC 2.0, you can delete them right away in PC 1.0.
To handle archived plans in PC2.0
Going forward, you could make use of grandfathering feature of Plans which is explained here, since you are creating new Plans only to introduce price change. This is supported in PC 1.0 as well