/* woocommerce < 2.1 */
add_filter( 'add_to_cart_text', 'woo_custom_add_to_cart_text' );
/* woocommerce > 2.1 */
add_filter( 'woocommerce_product_single_add_to_cart_text', 'woo_custom_add_to_cart_text' );
add_filter( 'woocommerce_product_add_to_cart_text', 'woo_custom_add_to_cart_text' );
function woo_custom_add_to_cart_text() {
return __( 'اضافه کردن به سبد خرید', 'woocommerce' );
}