Version 2.x.x
Level 30 is currently the cap for Fruit Ninja, which means you cannot gain more experience past this point. 

We’ll likely increase the cap as we continue to add more exciting content to the game, but until then, congrats on maxing out your level! 

Version 3.x.x
As of 3.x.x and up Level 100 is the new maximum level. If you are unable to progress past level 30 in this version, please contact support.