Update subfields ACF

update-subfields-acf.php

<?php
$fields = array();

// $dates = array of subfields to update
// $post_id = where to update fields

$repeater_key = 'field_58e1e3a5fe92f';

foreach( $dates as $tour_date ) {

    $date  = get_converted_date( $tour_date['schedule-date'] );
    $from  = $tour_date['schedule-from'];
    $until = $tour_date['schedule-until'];

    $fields[] = array(
        'date'       => $date,
        'time_from'  => $from,
        'time_until' => $until,
    );

}

if( $fields ) {
    update_field( $repeater_key, $fields, $post_id );
}