Including home improvement loan in rental property calculator

[Jonathan Steiger]

Is there a way that I can include a home improvement loan in the rental property calculator? 

For example, the duplex we have has a 25 year mortgage at a 3.75% interest rate.

If we get a 12k home improvement loan at 6% interest over 3 years how can this be incorporated into the calculator?

Is there a way to add repair costs that will be borrowed rather than paying with cash?

Any help would be greatly appreciated!