Hi Emily,It depends on how you want to handle the existing app in the
store. If you want to replace your existing app then you can use the
folio migration tool in DPS 2015 to migrate all your old content over,
create a new app, and submit that new app to the store to replace your
old one. Your readers will get the new DPS 2015 experience but will
still be able to access the old content (now as collections migrated to
DPS 2015, rather than folios in the old app). This option is available
for iOS ...