Clearing the game data will result in erasure of game progress, some of which when lost cannot be restored.
The in app purchases "All of the things" "Double Winnings" "Unlock all Quickrace Tracks" and "Unlock all the Cars" should be able to be restored. However any Career Cash or Career mode progress you had will be lost.
If any of the listed in app purchases are not being recognized when you load the game you can try the following: Firstly make sure you're logged in to the same Google Wallet/Play Store account which you used to purchase them with. If they don't unlock automatically you can try to "re-purchase" them from the store and your Google Wallet should recognize the existing purchase on your account and unlock it again for free.
In future we do not recommend clearing the data for our game!