Replace ContentBlocks values with new values

gistfile1.php

<?
$c = $modx->newQuery('modResource');
$resources = $modx->getCollection('modResource', $c);

foreach ($resources as $res) {
	
	$properties = $res->getProperties('contentblocks');
	
	if (empty($properties)) continue;
	if (empty($properties['content'])) continue;
	
	$content = $properties['content'];
	$content = str_replace('"color":"blue"', '"color":"secondarytext"', $content);
	$content = str_replace('"color":"red"', '"color":"primarytext"', $content);
	
	$properties['content'] = $content;
	
	$res->setProperties($properties, 'contentblocks', true);
	$res->save();
	
	echo $res->get('pagetitle')." REPLACED<br>";
	
}