As you get further into runs, you'll notice bonus items that you can
use to help you along. Powering these up can be done from the main menu.
You'll have to cash in your bananas and tokens though so it's important
to choose wisely. For example, if you're going into a challenge that
requires you to break through a lot of ice using the freeze ray, level
up the freeze ray by cashing in bananas. This will make the challenge a
lot easier and allow you to advance faster.
There are a few power-ups that are always safe bets and always
benefit you, and those are the ones that net you large amounts of
bananas. So be sure to level up the Banana Splitter and the Fluffy
Unicorn whenever you can. More bananas means more upgrades.