Automatically update Default contracts for customers on the 1st of the month

Hi Guys,

Most of out contracts are monthly (for billing purposes).
At the end of each month, we run a script to close all monthly contracts and create a new ones for the next month.
CommitCRM defaults all customers contracts back to global system, is there a way to automate this, even though they are new contracts being created.

Contracts are named below:

CSA-CUSTOMER.0005 - Last month
CSA-CUSTOMER.0006 - This month

Note not all customers have a monthly contract, some should stay global system.
Any help as always is greatly appreciated.

Ash

At first I want to explain how system selects a default contract when creating charge/ticket for Account:
When no Contract has been created for an Account, or when there is no active Contract for this date range, the 'Global System Contract' will be selected automatically.
When using Monthly (reccurring) Contracts) the system will automatically select the contract with the new date ranges when the previous Contract expires, even without closing old contract.
In order to prevent the situation when there is no Active Contract for Account we recommend to renew (by batch copy) the contracts just before the end of month
and then to close contract at the beggining of the next month (after the contract was expired).

Thanks,
Dina