Elite to Elite: Dangerous was a huge Jump
Same for:
- Wasteland to Wasteland 2
- Bard's Tale 3 to Bard's Tale 4
- Shadowgate 1987 to Shadowgate 2017
- Kid Icarus to Kid Icarus: Uprising is a fairly extreme example.
Basically all those IP that got stopped in the 80s/90's and then got a successor 20+ years later all qualify for the title.
Another game I would mention would be Wizardry VI after Wizardry V and, on a similar note, Wizardry 8 after Wizardry VII. It helps that there are 9 years between VII and 8, but V and VI had only a 3 years gap. Though here, it helps that the early Wizardry titles didn't change much since their inception in 1981, so those 3 years are technically more like 7 years of actual development.
While we're at it with old CRPG, Might & Magic V being followed by Might & Magic VI. Going from 2D to 3D (with 2D sprites and vegetation) while changing drastically how the classes and gameplay works (from turn-based to a potential manual mix between turn-based and real-time combat (you can turn off turn-based combat while in combat and turn it on seconds later again - good to avoid some missile for instance), and real time exploration).