Hello,
By updating HikaShop you won't loose any information. It will just update the files and add new columns in the database if required.
Your views overrides (that you have done through "Hikashop->Display->Views"), css overrides, language, configuration, orders, products will stay intact.
But careful if you have modified directly an HikaShop file and you didn't use the backend interface for that....
Note that making a backup is always a good security.
