By default, the Pre-Approval limit is 12 months which is set by PayPal. You can request PayPal to increase this limit.
Also, please review your Pre-approval settings in PayPal by Subscriptio under WooCommerce Checkout
Please have a look at this snapshot for reference: http://prntscr.com/9xz6gc
Take note that, you must enter the value of Max All Payments Total as $2000 or equivalent in your base currency.