How can I post /cart/update.js on checkout in Shopify Plus?

I’m trying to update the cart.attributes property on the checkout page.

On the cart page, I do this by running the javascript code using jQuery.

$.post('/cart/update.js', { attributes : { "my-attribute": "my-attribute-value" } } );

On checkout page, I ran the code:

$.post('/cart/update.js', { attributes : { "my-attribute": "my-attribute-value-updated" } } );

The code does not update the “my-attribute” value. Is there any other way to change it? Or in some cases even delete it?

Thanks,