Saving a variable to the workbook does not change the state of the variable in any Maple kernel backing the document. This means that if the variable z has already been accessed it will continue to retain the it's value regardless of whether the variable is re-saved. If you want to force the variable to the saved value then do a
Also you can use a maple code attachment like you would an external .mpl file. Execute the following line
If you want to share state between multiple worksheets in Maple then you can also use shared kernel mode.
Tools->Options->General->How should Maple handle the creation of new Math Engines?->Share one engine among all documents