Update formula in cells based on list selection

Hello,

I am a newbie to excel and seek your expert help. I have a dropdown with these values:

2013-Q1
2013-Q2
2013-Q3
2013-Q4

And, I have formulas in several cells like these one below.

=COUNTIFS('Completed'!D2:D2000,"*SQLUpgrade*",'Completed'!C2:C2000,"2013-Q1")
=COUNTIFS('Completed'!D2:D2000,"*OSUpgrade*",'Completed'!C2:C2000,"2013-Q1")
=COUNTIFS('Completed'!D2:D2000,"*APPUpgrade*",'Completed'!C2:C2000,"2013-Q1")

My requirement is, if I select 2013-Q3 from the dropdown, the string in the above formula "2013-Q1" (in all the cells) should be updated to "2013-Q3". So that, it will update the count based on the quarter. Similarly, if I select 2013-Q4, the string in the above formula "2013-Q1" should be changed to "2013-Q4". Can anyone provide macro to achieve this task? Thanks a ton.

After the ! in each line, place the address (e.g. C4) of the cell associated with the dropdown.