How To Respawn The Ender Dragon,
Do you need the dragon egg to Respawn the Ender Dragon?
You cannot get another dragon egg in your world without cheating. Dragon eggs have no practical benefit and they exist solely for cosmetics, but even so, respawning the ender dragon does not spawn another dragon egg.
Can you Respawn the Ender Dragon infinitely?
The Ender Dragon spawns naturally in The End when the Player enters the Dimension. But once killed, it can only be re-spawned by placing four End Crystals around the Exit Portal.