I believe Aoe4 should implement the Ransom mechanic from AOE3.
Each time Jean is killed, the player that killed her get a portion of the gold spent to revive her. Something like 50-100% of the ransom gets sent to the person who killed her last each time. And the only way to NOT have the killer get paid is to allow Jean to naturally respawn which of course takes longer so there is a drawback to losing her either way.
You pay the ransom or you wait. This is a way to balance her respawns without JUST making it cost more and more resources.