The best replacement for replay is gameshark.

The best alternatives to replay are rated as following:
★★★★★  gameshark
★★★★★  tivo
★★★★  rude boy
★★  contour
★★  action replay max
★★  starmate replay
★  repeat
★  sportster replay
★  codebreaker
★  code breaker
★  sportster 4
★  margarito
★  reply
★  rude boy dj hero 2
  rihanna - rude boy
  r4
  an event
  rude boy dj hero
  golmaal 3
  gamestop
  rihanna rude boy
  game genie
  gts

Your alternative for replay is not listed? Suggest!
Speaking about replay, one probably shouldn't forget about r4.

Other search terms related to replay and their ratings are:
★★★★★ r4
★ pokemon platinum
action replay
halo 2
You have in mind a companion for replay and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of replay in all years. Click on graph for more.
replay
gameshark
tivo