Instead of ladder reset, they should do chronicle reset as well. Will definitely bring back players
How about just add things to the chronicle?
Reach level 99 on SC
Reach level 99 on HC
Find every rune (only eligible from picking up a rune from a monster, can't be picked up from being dropped by someone else or traded)
Eth only holy grail (Where it can applies obv.)
Etc.
Some of these could even be broken down into categories, but just a start.