You know your kid.
Your kid might or might not be able to raise his/her grades, and if you know now that there aren’t any changes coming, then work with the numbers that your kid has now. Neither you nor your kid need to exhaust yourselves fighting about grades.
Your kid might or might not be able to score high enough to get NMS status with the PSAT, and if you know now that your kid won’t, your kid doesn’t have to waste any energy prepping for or taking that exam. Go out to brunch that morning instead. If you know now that your kid won’t score well enough on the ACT or SAT to land merit-based aid, or to get into X, Y, or Z, then base the list on A, B, and C instead, and read through www.fairtest.org
Keep your own head screwed on straight through this process so that you can help your kid keep his/her head screwed on straight if necessary. If your kid was born with a screwed-on-straight head, thank your lucky stars for that!
And once again: Love the kid on the couch.