Reflashing means erasing the flash memory: it's like formatting an HDD and reinstalling the O.S.
What does it mean that you lost your backup? The personal backup? The FullBackup?
A backup can't be lost, it's a copy. Maybe you meant you couldn't import your personal backup?...
But this is normal. What really counts is the bouquet backup and you can do that in many ways. The rest is much better not to reimport, even when possible, but it's better to reconfigure everything.
And, as a good practice, before flashing next time perform a FULL Backup, in order to restore it in case you like or, also, to use it to install the old image in multiboot.