Was it ever explained why Glados's physical appearance change in 2?

[gluffofficial]

Was there a story explanation or did they just decide it was time for a redesign?

[Sinister80s]

redesign

[Renfrew]

There are so many redesigns in Portal 2, that it is considered that Portal 2 is a retelling of the first game

[booty warrior]

BOTH THAY REBUILTE BETTER

[omegaRuby]

Yes, I think that the nanobots rebuilt her. I was actually once confused about why GLaDOS looked different in 1, because I thought the OG design was from 2.

[MaxCE]

and add to it the fact she was outside aperture after portal 1 chances are they salvaged her AI and rebuilt her. but didn't have access to boot her up. only wheatley had access.

[Andy]

i'm pretty sure they found glados v.1.0 in the bird ending of portal 2 co op where there was a nest above her head, but portal 1 glados is probably glados v.2.0 because they are pretty different now that i think about it.

[MaxCE]

No look at the comics v1 is the one you see in Portal 1.

[DantheDragon16]

She does say at the end of the battle when her monologue is sped up that she had saved a backup of her brain hence the GlaDOS song during the credits