Please do not uninstall the application on your Salesforce org when there are newer versions of dftly Time Tracker available on App Exchange. If you Uninstall the app, all the data related to Time Tracker like Time Tracker Users, Time Tracker details and other details related to Time Tracker objects will be lost. You will have to process OAuth again when you install dftly Time Tracker and may have to create Time Tracker Users again to access dftly Time Tracker on your handset.
You should just upgrade the application when a new version of the Time Tracker comes out on the AppExchange.
Simply click on the Upgrade button in AppExchange and upgrade Time Tracker to the latest available version.