Well,
after you complete you process inserting data in form2 you have to bind form1 grid again on page load event because if you are not bind it or not refresh that form it should saw old record so you have to write code on page load for binding grid.
This will definitely solve you problem:
http://stackoverflow.com/questions/7797975/how-to-refresh-a-form-from-another-form[
^]
http://stackoverflow.com/questions/15896135/how-to-reload-form-in-c-sharp-when-button-submit-in-another-form-is-click
And accept as solution and vote if solve your problem.