Thanks for your posting and considering Aspose.Cells.
You can create a template file in MS-Excel and then load it in a Workbook object using Aspose.Cells. Then whatever changes you will do with the Workbook object will not affect your template file. Then you can save your Workbook object into some other Excel file.
Please see the following code. It loads a template file which was created with MS-Excel, then it adds some data inside it using Aspose.Cells and then saves the workbook object as output file. As you can see, output file looks like a template file with some data inside it but there is nothing changed in the template file.
I have attached the template file, output file and screenshot showing the outcome for your reference.
//Load your template file inside a workbook object
Workbook workbook = new Workbook(“template.xlsx”);
//Access the first worksheet
Worksheet worksheet = workbook.Worksheets;
//Add some data inside the cells
for (int i = 1; i < 9; i++)
Cell cell = worksheet.Cells[i, 0];
cell.PutValue(“Test-” + i);
cell = worksheet.Cells[i, 1];
//Save the workbook object as an output file