By using the Financial management application year update utility, you may increase the number of years by altering the End year. you are allowed to decrease the number of years. And the start year can not be altered. Its grayed out.
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I do not believe that you can use the current version of the Year Update Utility. However, you can create a new profile and reshell your current application.
This should be a straight forward process. I would more worried about the impact of your "new" data in the existing data.