Before your current rental period expires, you can extend it from the Donkey app.
Tap on the rental you want to extend, then on the extension option - see screenshots below. Choose one of the available options for the extension period. The good news is that the extra time costs less than the full price - that's how happy we are you want more Donkey time!
To get an idea of how the rental extension system works, take a look at the tables below.