If I am understanding this correctly, you can copy grade plans from year to year.  If you are in your current year grade plan hit "copy" and the previous year's grade plans will show up in a drop down.  You can also roll your grade plans forward each year in the Master Rollover.  It is under the Grading section.  If they are not going to change significantly from year to year then this is the best way to do it.  It will copy them all to the next school year.  But, you still have to ability to make changes without affecting the previous years.