Am I able to do a deposit with a payment on a Form?

My form: https://form.jotform.us/72265136365154

This is a registration form and they select how many people and nights they will be staying, but I want to be able to offer a way for them to just pay deposit instead of the full amount.

Is that possible?

Unfortunately, it's not possible to achieve that, our current payment processing integrations will only allow you to charge your user and once the submission has been done there is no way to process the charge again. 

You could however, perform some calculations and charge your users only certain amount, then send them instructions about how to send you the payment with the rest through an email auto-responder.

Related guide: https://www.jotform.com/help/26-Setting-Up-an-Autoresponder-Email 

I would also recommend you to take a look on the following thread: https://www.jotform.com/answers/1026804 

Please let us know if this would work for you.