Not sure about that. Reformatting the SD card would wipe everything off the card, including your backup file, so unless you've stored an additional copy elsewhere, e.g. PC, flash drive, etc, you've defeated the purpose of having a b/u app. One of the features that SPB advertises is that the backup can be used when upgrading or replacing a lost/stolen device. I think the best answer to this question would be found on the SPB website.
www.spbsoftwarehouse.com