I have a worksheet that does calculations based on the last 2 weeks of data, so basically I enter data like this:

SHEET1 
Week1                        Week2        
SKUs     Quantity            SKUs     Quantity    
100         5                120         4
103         10               103         6  
110         3                104         4
Every week I have to replace the Week1 and Week2 columns, but basically I just move Week1 to Week2 and I add in the new week's data.

I'd much rather be able to just create a "rolling" master list of every week in a new SHEET2 and have SHEET1 automatically populate itself by pulling the last (or first depending on your pov) two weeks of data. The data will always only be only two columns (so I don't have to worry about that), but the length (number of rows) may vary.

SHEET2<-- new sheet next week with added week of data (no headers)
100        5                 120       4                100        5
103        10                103       6                113        9 
110        3                 104       4                110        6

SHEET2<- SAME sheet next week with added week of data (no headers)
100        5                 120       4                100        5                  110       4       
103        10                103       6                113        9                  103       2
110        3                 104       4                110        6                  105       4
etc.