how do you reverse this spell or return to your previous race?

Quote from bearslord >>

Fastest build-breaker of the wild west

damn skippy. I was a deep gnome sor-lock now I am a goliath. oof.

Is there an "official" update to this, with the new races that have come since this was published?

reject humanity, return to slime

I like this spell, roll on the table or discuss with the DM as "or the GM chooses a form." Beware, min-max builders :) 

Quote from GenericRpgNPC01 >>

The intention of the spell is that anything that came from the original race is lost and replaced by the new race.
This includes things like fey ancestry, aasimar healing hands, half orc relentless endurance.
And things like lizardfolk hunters lore skills and half elf extra skills.
Raw (and I believe based off the wording, as intended) you also replace your starting language
As that comes packaged with the race

So you lose everything from the original race (I'd assume you'd get a refund if you took a racial feat for the original race though. If a DM doesn't let you do that they are a ****** in my book)

Say you go from, dragonborn, to elf. You'd need to learn how to make dragon noises with an elven tongue. You'd need to relearn the language with your new physiology. Apparently a new language rolls off your tongue as elven is much easier for you to speak, and due to your new brain chemistry you now understand everything said in that language... 

Now say you go the other way... elven accuracy doesn't dissappear. You learned to be more accurate and that knowledge stays with you. Were you a drow? Cause you still get the spells you learned from studying with your people its more of a ritualistic homage to Lolth than something you can do. 

Tiefling? Well technically your soul has infernal ties so flames of phlegethos is you leveraging the planar power of your soul not a chemical reaction. Part of you is soul made flesh as planar beings have a soul that is their body. 

I'd love to see a player reincarnate multiple times and learn racial Feats from multiple races "you wouldn't believe the things I've done to get where I am" says the dwarf, nee dragonborn, nee half Orc, nee elf, nee duergar. 

A new version of the reincarnation. Spell should be made that allows for newer printed races to be possible.

What is to happen with age? (lifespan and such)

So how I think this spell works is that it forms the body of a person, but exchanges their race and any attributes of your previous race that you got from genetics alone, such as (maybe, this is according to your DM more than the spell itself) genetically learned languages (see Dragonborn, and once again, this is according to your DM), stat bonuses, and (once again, maybe) spells that you got simply because you were an elf or something. What I mean by that is, say you were a Tiefling before but are now a human, your Thaumaturgy/Hellish Rebuke/Darkness would go away. As I have mentioned multiple times, ask your DM this stuff, because I haven't found anything official that clarifies this yet. It's just how I run it if people don't mind it too much.

How does this spell affect sex and age?

If someone is brought back with this spell, do they come back with full health?

So WotC, when are you gonna errata this severely outdated table? It needs to updated all the way up to the fantastical races from Monsters of the Multiverse.

Indeed as i have recently became a changeling

I like gnomes

This spell is going to make so much more sense with One D&D version. Replaces race, but not background, so it's way clearer that your ability score, languages, skills, feat, etc., all remain the same, and only your body changes and the hard physical race stuff

You touch a dead humanoid or a piece of a dead humanoid. What constitutes "a piece"?

Quote from Commander579 >>

Why are liches a thing? Seriously. It is like living forever but with no overt side effects. Or a clone? 

 Well firstly, you'd need someone else to do this to you, secondly, clone is far less handy, thirdly, the side effects are one of the best parts!

Given the new playable races officially added into the game, do you think the chart might need some updating?

That would be great. I was a fairy, but now I'm a hill dwarf. I could get this effect again, but RAW it's impossible to become a fairy again. Wild Magic is interesting.

My thought would be that elves only have the elven language due to having been raised as elves, hence "custom lineage" allowing a character to be an "elf" without the elven language. Then there are "racial" abilities that are truly tied to the "race" such as darkvision...or flying...or exceptional dexterity or intelligence (yes, sorry, but intelligence is genetic, and so can be bodily control i.e. dexterity), whereas languages are a learned trait.