Yes, REPRIEVE is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, P 3, R 1, I 1, E 1, V 4, E 1.

Is it a valid word?

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

a (temporary) relief from harm or discomfort
an interruption in the intensity or amount of something
a warrant granting postponement (usually to postpone the execution of the death sentence)
the act of reprieving; postponing or remitting punishment