to back up you can do:
copy current-config backup-config
to back up the config
Now to restore the ips config to the default you can erase the current-config and/or the backup-config
or you can
Reboot the appliance.
The following menu appears:
GNU GRUB version 0.94 (632K lower / 523264K upper memory)
-------------------------------------------
0: Cisco IPS
1: Cisco IPS Recovery
2: Cisco IPS Clear Password (cisco)
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and you select 1