If you get the new page to work, you should be able to just paste its contents and TV values into the old one, no?
If not, a rewrite rule in .htaccess would be the most efficient way to redirect users to the new page.
Another way to go would to find and rewrite the links to the old page and make them links to the new page.
Finally, you could put a snippet tag at the top of the old page for a snippet with this code:
$newId = 12; // change this to the ID of the new page
$url = $modx->makeUrl($newId, "", "", "full");
$modx->sendRedirect($url);
If you want the URL to remain the same, you can also use $modx->sendForward($url) instead of $modx->sendRedirect($url).
