When you unload the ender crystals used for the respawning of the ender dragon for example by killing yourself and then loading them again the respawning sequence will continue but the BeamTarget of the ender crystals won't get updated.
- Kill the ender dragon
- Start the respawning sequence
- Kill yourself or unload the portal
- Come back to the portal
The sequence will continue but the ender crystal beams do not change.