Your account and data is stored on our servers, not on your phone. You can log in to your Ovia account on any phone where the Ovia app is downloaded. Deleting and reinstalling the Ovia app will not delete any of your data.
When you download the Ovia app on your new phone, use the same email and password to log in and your data will be there.
Please just be sure that you know the email address your Ovia account is associated with and have access to that inbox, in case you need to reset your password for Ovia. You can check what email address your Ovia account is associated with by going to "More" in the bottom bar > Settings (in the "ACCOUNT" section).