Yes, you can use our "Schedule Price Change" feature to schedule a price change for a plan and any associated add-ons, which will affect all new and existing subscriptions on the specified effective dates.
To implement this change, go to Configuration -> Plans -> Locate the plan you want to update and click on it -> Click Schedule Price Change.
From there you will see the option to schedule your price change for new subscriptions and existing subscriptions:
Below this section you will also be able to schedule price changes for any add-ons or setup fees attached to the plan:
Don't forget to click "Schedule" and then you're all set!