Here is an alternative method which follows the line of copying the calculations multiple times (but without really doing so).
You simply set up two worksheets. The first one (I called it "Calc") would be your 25 page sheet but without the variables defined you want to change. Don't mind the red errors for now.
Example of Calc.xmcdz:
Now create another worksheet, define the variables, insert a reference to Calc.xmcdz and display the calculation result. Then define the next set of variables, insert the next reference, etc.
Inserting a reference acts like you copy the content of that file in that place of your new worksheet. You could as well put your calculations in a collapsed area and copy this area multiple times, but then you will have more work if you need to change something in your calculations as you will have to do the copying again. The drawback of a reference on the other side is that you have to handle and keep together two different files.
As you probavly use units the method with the matrix consisting of all variable sets will not work in Mathcad 15 and below because we are not allowed to keep values of different dimensions in one matrix. But is should be no problem to provide the values singly as shown in the last example below or you may use a single vector for each variable:
