FromDate & ToDate to be Changed after 14 Days.

Dear I have table called Mst_Crew.

Fields are

Cr_No numeric

Cr_Name varchar

FromDate date

ToDate date

I need to change the FromDate & ToDate when the ToDate pass the currentdate then need to be add 14Days on FromDate

For Example

CrNo CrewName FromDate ToDate

1 A 29-Nov-15 13-Dec-15

2 B 06-Dec-15 20-Dec-15

3 C 13-Dec-15 27-Dec-15

4 D 22-Nov-15 06-Dec-15

The Next Change will be

CrNo CrewName FromDate ToDate

1 A 27-Dec-15 10-Jan-16

2 B 03-Jan-16 17-Jan-16

3 C 10-Jan-16 24-Jan-16

4 D 20-Dec-15 03-Jan-16

It means that.

When Todate

How to do this in SQL

Thanks

Basit.