Transferring from 7.0 to 7.1 - how to avoid loss?

Hi all!
I've had a 7.0 site since 2020, and recently decided it needed a redesign. I started a trial (using 7.1) and spent a lot of time on it before discovering that swapping my subscription over to the 7.1 site isn't as easy as I expected. 

Since I've already spent the time creating and refining it, I'm trying to find the best way to cancel my 7.0 site (paid annually) and start using the 7.1 version without wasting too much money. Squarespace's guide recommends contacting them to see if you're eligible for a pro-rata refund after cancelling your site, but from what I'm reading here that seems only applicable for Circle members and designers - please correct me if I'm wrong!
Swapping from annual payment to monthly only seems to be possible after the current billing cycle, and I can't find any way of extending the free trial more than 7 days (as I'm not a Circle member).

I'm grateful for any suggestions, Thankyou in advance!

Damn... I was hoping there was something I missed. 🙂
Thank you for the help!