Yes, REPLACED is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, P 3, L 1, A 1, C 3, E 1, D 2.

Is it a valid word?

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

substitute a person or thing for (another that is broken or inefficient or lost or no longer working or yielding what is expected)
take the place or move into the position of
put something back where it belongs
put in the place of another; switch seemingly equivalent items

Also: supervene upon, put back.