Will the upgrade grow up after the level increases?
Yes, it will increase. When you at level 1, you can get 250Mb data bonus. Then when you at level 2, you can get 500Mb, etc.
The upgrade will increase as your progress throughout the levels. The number of upgrades you can use at one depends on the number of slots available to you.
You can learn more about Upgraes and Perks here : https://fizz.ca/en/faq/what-do-i-receive-my-rewards-program
Hope that helps :)