Need Forumla to Re-Calculate when Date Changes for Close Month

Hi, Please see the worksheet that I've attached. What I am trying to do is to get the Bookings, Sales, and GM to re-calculate correctly when the date changes. For example, when I change the Close Month to December in K13, I would like the Bookings to Move from N14 to O14, while showing the correct weighted value of H14. At the same time, I would like Sales (N14/J14) to move from O15,P15 and Q15 to P15, Q15 and R15 respectively and the same for the GM. Sales is always one month after the booking occurs.

Hope this makes sense. Thanks.