update_post_meta with Custom post_type

I have a custom post_type called, "lessons" which has meta fields that I populate with a gravity form.

I then have a "duplicate" of the form that loads on a separate page and dynamically populates the content with the meta information and is supposed to let people update the post.

I have a gform_after_submission hook to update the meta data, but because it's a custom post_type it's not working.

Here's what I have for the function to update the meta...

function gf_edit_plans( $entry, $form ) {
    global $post;
		$monday_lesson = $_POST['20'];
		update_post_meta($postID, 'monday_lesson', $monday_lesson );
}
add_action( 'gform_after_submission_10', 'gf_edit_plans', 10, 2 );

Any ideas?
I've been racking my brain on this one for hours!!

Thanks.

It is grabbing it... but it may not be grabbing it correctly.

Meaning I can echo it onto the page, but when I added in what you gave it "updated" the post, but it simply deleted all the entries.

Have a look...

Here's the template page...
http://pastebin.com/kUHyp19H

And here's the functions page...
http://pastebin.com/3L6TZk2m