The U's saw their League One play-off hopes dented in a 3-1 defeat by Fleetwood on Wednesday following their EFL Trophy final loss to Coventry.
"We've got to make sure we bounce back and end the season on a high," Ruffells told BBC Radio Oxford.
Oxford are seven points off the play-offs with five games still to play.
"It's all about the performances from now on and making sure the gaffer knows we're good enough to stay in the side," Ruffells added, after making six appearances in the space of 19 days for the club.
"It's been a difficult and disappointing few days for the club. I thought we gave a good account ourselves (against Fleetwood) and bounced back well from Sunday.
"I don't think they caused us too many problems and it's disappointing really."
Oxford United midfielder Josh Ruffels urged his team-mates to stay positive after double disappointment in cup and league in the space of four days.