WooCommerce - Store Credit v2.1.12

Generate store credit coupons that enable customers to make multiple purchases until the total value specified is exhausted or the coupons life expires. Create store credit style coupons in your WooCommerce store. Generate store credit coupons that enable customers to make multiple purchases until the total value specified is exhausted or the coupons life expires. For example a $50 store credit voucher used at checkout for a $30 purchase will allow for a future purchase of $20 or until the total value expires or is exhausted. Customers can also buy products worth more than the remaining store credit and pay the difference at checkout. Store Credit includes a handy utility for generating and emailing a credit coupon to a customer by entering their email address and the amount.

DEMO:
https://woocommerce.com/products/store-credit/