Hey Tim,
Email Programs are meant for one-time sends and cannot be reused.
We suggest to clone your email program everytime you want to send a new email. Thus, everything will be set the same and all you will have to do is set the date and pick a new email.
Alternatively, you can set up a Smart Campaign to run weekly. You will be able to use the same Smart Campaign this way and just select a different email in the flow every week.
Best,
Will