If you need to resync the data on your device to your PC you can do so easily following the instructions below.  Also note that the data in your PC will not be duplicated but the data coming from the device will replace the corresponding entries on the PC side should they have been edited after sync was done.

iOS devices:

Go to Settings/Synchronization and tap the red button at the bottom to mark all as unsynced.  Return to the Home Screen and sync your device

Android devices:

In the data area you want to resync such as the Flights list, long press and a menu will appear and then choose "Mark All as Unsynced" and then you can sync the device again from any screen or the home screen

After the steps above are accomplished login to http://nc-software.com/sync and verify your data is in the cloud.  Then from Logbook Pro Desktop make sure you are signed in to your NC Software account, the same account as on your device (app) and then click Cloud Sync / Sync Now.