Hear me out...refrub additions to existing rides instead of new ones
My family and I love Efteling and we go there 2x a year easily (staying at the hotels too).
We were talking the other day and both my wife and I thought new rides are awesome and all, but some older ones could use TLC.
These could be minor touch ups that could be cheap and bring some rides up to 21st century standards:
Villa Volta: smoke or light effects, possibly a halo graphic ghost lady during the flips.
Vogel rok: stronger lighting with those neon artefacts inside the ride, better starlight projectors.
Python: on board music and sound effects of a snake hissing or something
George Draak: a moving dragon and occasional fire effects
Fata Morgana: more fog effects on the water to add to the dreamy oriental ambiance
Max Moritz: more trees or theming in general around the track.
Pirate ship: forgot its name but a large animatronic whale in the water in front of it.
None of these are necessarily expensive additions, but they would bring some life back into the fading rides. Don't get me wrong, we still love them, but they need some attention. Plus, it shouldn't cost Efteling much to do these.