Saturday's 2-0 home defeat by Southampton left the Royals bottom of the table and eight points from safety with just six games remaining.
Nigel Adkins' side can still mathematically stay up and 26-year-old defender Mariappa insists the team will not be throwing in towel, with their next test the home game against Liverpool next weekend.
"Every game is massive for us now and we'll give it everything on Saturday," said Mariappa. "We're trying to survive and everyone is focused on that.
"Everyone is playing out of their skins to make sure we stay in this league. That's the main focus of everyone at the club.
"There's going to be pressure at every moment in all these games now. Every point is now precious for us.
"We'll have to keep going and look to get ready for the next game.
"There are enough points available to stay up but the games are running out now.
"We were written off before the season started so every game carries its own pressures anyway, but now we need to really get the points on board."