Leasing on 36 months – possible after 24 months of vehicle change?

Hello together, the following facts: We leased a Mini Roadster S about 24 months ago and are still enthusiastic about the car. Overall running time is 36 months, i.e. about 1 year remaining time. Now I would like to know if it is possible to switch to another vehicle (BMW 320 Touring or 4 Series Coupe, etc.) even before the entire 36 months have expired. If it is possible, which expenses would I have to reckon with? Thank you for your answers! uß Florian