Challenges after Reality

[Raptor]

Do I need to do all challenges again after every reality?

[BrownianMotion]

Yup, until you reach* the relevant milestone or upgrade which will carry over/complete those challenges

[Raptor]

Can't remember what upgrade unlocked all challenges

[DUMBHA]

At least with the boosts from the auto-achievements and power glyph, (And if you took the time to get it before you did your first reality, the second "Yo dawg" 'chivo is a huge QoL speed-boost) you should be able to turbo through most of the early basic challenges much faster then before. Besides tickspeed... Still gotta manually slog through that one on reality 2/3 at the start

And if you know the tricks, you should still be able to power through infinity challenges as well with said boosts.

And as for the auto complete upgrades. The 'RU' AKA Reality Upgrade called "Existentially Prolong" will let you start with 100 eternities, which lets you start with the eternity milestones that auto complete all the normal/infinity challenges from the start, you should be able to get that on your 3 or 4th Reality if you played smart or slow. (Smart as in, farm a bit longer to earn 3 RM on your first reality, then 6 more for your second. So you can get 1 of each top row RU). then farm 15 RM for it on your next reality.

And as for Eternity challenges, the PEC1-2-3 Perks will auto-complete one every 60/40/20 mins, While the ECB perk will let you complete multiple tiers of a challenges in one go if you got buff enough stats.