Clocker 0 Newbie Poster

Hi guys
i have a form in my application that calculates the invoice of all the charges of a patients. there is a form that calculates the room charges of the patient but it will no update the previous record.
what i want is the room charges form to calculate and add the room charges of the patient then display the result in listview. if i add a new room charge i want the form to update the total charge in the listview.

thanks