Ted here from Shopify Support, thanks for reaching out to us.
I've taken a look at your store and at the moment we wouldn't be able to apply a free trial to the account. On saying that, as you've paused the store, you could duplicate your store's data as shown in this guide and transfer it to a new store which would have the 90-day trial automatically added. Is there any feedback you could provide for Shopify in regards to why you paused the store? How are you finding Shopify so far?
If there is anything else I can help you with, please let me know, I'm happy to help!