Yes, RESPIRED is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, S 1, P 3, I 1, R 1, E 1, D 2.

Is it a valid word?

RESPIRED is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

breathe easily again, as after exertion or anxiety
undergo the biomedical and metabolic processes of respiration by taking up oxygen and producing carbon monoxide
draw air into, and expel out of, the lungs

Also: take a breath.