I think it is not possible.
All NSX Edge configurations (logical routers and edge services gateways) are backed up as part of NSX Manager data backup.
Taking individual NSX Edge backups is not supported.
Probably you need to redeploy EDGEs.
It is unsupported to perform individual backup of Edges/Control VM etc. The ease of just restoring NSX manager to recover all the components is far more perfect than doing it in bits and pieces. What you should understand is , NSX backup/restore is not like a traditional back/restore were we spend time on agent/agents less , file based, VM based etc discussions , all we need is backup the NSX manager and VC ( If it is vSphere with NSXv) and we are prepared for the worst case scenarios.