Thanks for the easy solution. I can use this for different files I have. But not for the 50+ files which needs modifications each month.

Let me explain the modifications. P.S. I am giving the example of what changes i require while changing from June 2013 to July 2013.
'Summary' sheet changes:
- A1 changes to "GENERAL MAINTENANCE VOUCHER SUMMARY - JULY 2013" from JUNE 2013 and so on each month.
- A3:A150 need to replace -06- with -07- (06 = June & 07 = July). So the July 2013 file will have GM-07-0001 and so on.

'Format' sheet changes:
- By the end of each month, cell J8 will have reached GM-06-0100+/-. SO when the new excel is generated, the value in J8 should be replaced to GM-07-0000 (not 0001)

Now, you see I have to do this manually for 50+ files each month. So any suggestion or help will be highly appreciated.