How to refresh view whenever a discard button is clicked? I want to clear all page context and references whenever a top discard is clicked.

Actually what I am facing is that I have a one2many view (order_lines of sale.order) which I am populating by overriding the default_get of sale,order. This one2many view is populating as I want but when the form view is closed and reopen, then default data is populating twice. It goes on increment whenever I repeat this process. I am assuming that this is causing due to view context that already contains previous data in it. And default_get keep adding further data to it.