Upgrading customer to higher Paypal subscription price

I need to change the Prosite level to a higher-priced level. They originally used Paypal to subscribe, but Paypal does not allow me to manually increase a subscription amount beyond a certain percentage (I think it's 10% increase). I have also added Stripe to the Payment gateway options for the Prosite checkout.

My question: is there any way to increase the Paypal subscription from my backend dashboard admin, other than canceling the old one and opening a new Paypal subscription? I know I can have the person go through the registration process again and choose the higher priced level, but that form asks them to create a new username, email, etc. That seems like a lot of trouble for them. Plus, a new site will be created and I don't need this.

I can also create a stand-alone Paypal subcribe button, but this does not allow use of a credit card (because I'm not paying the extra $50/month). The subscriber has to be a Paypal member.

Any work around solutions? It looks like Stripe has the capability of creating custom forms, but I don't have the developer skills to do this manually for my site.

Thanks, Joe.