In that case the saved games from Season 1 were probably removed during the uninstallation of the app. If you have a backup of those saves you might be able to copy them to SD:/Android/data/com.perverteer.tftuv/files/saves/
and continue the game in Season 2.
One of the major reasons for having multiple seasons is the app size limit imposed by Android, application bundles can't be larger than 2GB.