Can I automate the whole subscription renewal process for my customers?

Yes,

With the helps of subscription management software, you can automate the entire customer subscription renewal process.

There are plenty of subscription billing software out there which manages all your renewal task efficiently. Apart from this, they also perform a number of tasks including generate invoice to their customer, send notification about the successful/unsuccessful transactions, protect you from the frauds and much more.

Here is the list of those software:-

Pabbly Subscriptions

Recurly

Chargify

Chargebee

Fusebill

These software not only serve your customer in a better way but also boost your business revenue.

Hope this helps!