HA soft switchover with session persistence

Hi, Is there a way to maintain open sessions during a switchover from active to standby (I don't mean a failover, when the switch is more or less forced, i mean a situation, when I make the standby F5 go active). What I want to achieve is to keep open connections on the previously active F5 and open all new ones on the actual active. So after some time I'd be able to do my maintenance on a completely traffic free device without clients having noticed anything.

I looked into session mirroring, but this will not work for me, since Active and Standby are in separate data centers