Eppiah dropped out of the team for the first leg at Field Mill on Saturday and was only fit enough to play 35 minutes, with Idris Kanu starting in his place, while Appéré made it past the hour-mark before limping off.
"We will need to have a look at Louis,” said manager Jon Brady.
"We had to shuffle the pack a little bit because one or two weren't really ready for the game and that's the way the cards fell for us.
"Josh came on and he was good and he posed a threat and we got some really good final third entries.
"There were some crosses into the six-yard box that we were just a whisker away from but we know what we can do.
"Josh just wasn't ready to start. Who knows if he will be ready for Wednesday. I'll talk to the medical staff and see what the situation is."
Doubts remain over the fitness of Aaron McGowan, but goalkeeper Liam Roberts is definitely available for Wednesday’s game at Sixfields after serving his one-match suspension.
Jonny Maxted started in his absence at Field Mill and made an important stop from Rhys Oates at 2-0.
"I think it's a routine save for Jonny,” Brady added. “He's a good goalkeeper and I expect him to save that but he's acquitted himself well and I'm really pleased for him.”