The way I could see an NG+ is :
You keep all cosmetics;
You keep all upgrades that are not story related (health, force, abilities);
Story related powers/ upgrades and the abilities depending on them will be locked until you unlock the base upgrade/power through game progress, then everything you had unlocked is unlocked automatically;
Upgrades via finding secrets (health, force) can be done again in NG+;
Difficulty goes up by one level (i.e. a normal difficulty NG+ gets the enemy AI, aggression, and damage of hard difficulty, and so on - with a new extremely hard difficulty for very hard);
Different enemy composition, adding inquisitors or other difficult enemies (even generic lightsaber wielders) in different places and possible slight buffs to enemy stamina to make things interesting.
That would definitely make me want to play this again.
