This code changes the _Make this donation_ string

change-givewp-text-recurring.php

<?php
function my_give_text_switcher( $translation, $text, $domain ) {
	if ( 'give-recurring' === $domain ) {
		switch ( $translation ) {
			/*
			 * Changes the "Make this Donation [monthly/weekly/daily]" text for
			 * a donor's choice recurring checkbox.
			 */
			case 'Make this donation %1$s' :
				$translation = __( 'Make this membership automatically renew %1$s', 'give' );
				break;
		}
	}

	return $translation;
}

/**
 * Conditional for gettext.
 *
 * @param $form_id
 */
function my_custom_give_confirm_form( $form_id ) {

	// Customize form title here or remove conditional for all forms.
	if ( $form_id == 2010 ) {
		add_filter( 'gettext', 'my_give_text_switcher', 10, 3 );
	}
}

add_action( 'give_pre_form_output', 'my_custom_give_confirm_form', 10, 1 );