Change Account Expiration Date

I have about 2000 accounts.  Is there a way to do a script to change the account expiration date (accountexpires field) from July 31, 2015 to July 31, 2016 with the Description "Specialist"?  So, I only want to change the account expiration date with the word "Specialist" in the Description field.  If it is not possible to filter by Description, just setup a script to change the account expiration date.

Thanks.

Diane

Diane