add_action( 'woocommerce_simple_auctions_outbid', 'woocommerce_simple_auctions_extend_time', 50 );
add_action( 'woocommerce_simple_auctions_proxy_outbid', 'woocommerce_simple_auctions_extend_time', 50 );

function woocommerce_simple_auctions_extend_time($data){
	$product = get_product( $data['product_id'] );
	if ('auction' === $product->get_type() ){
		$date1 = new DateTime($product->get_auction_dates_to());
		$date1->add(new DateInterval('PT30S'));
		update_post_meta( $data['product_id'], '_auction_dates_to', $date1->format('Y-m-d H:i:s') );
	}
}