If the KF miles were still in your account, they have been extending the life of KF miles on and on, for 6 months at one time.
But as you have already made a redemption, I am afraid that it, kaput, use it or loose it.
See, you have a points booking, meaning that the points are no longer yours, even though you have not used it as such, but the points have been "used" for those seats.
You could try phoning up, and see what they say, you might loose half of the points as a penalty, or loose part of the points as a penalty, and the rest might come back to your account.
But as for a sure cert, I can't say.
I flew with SQ and AirNZ, putting in my KF FF #, first in 2017, points were to expire in 2020, but they have extended the life of my KF miles, but I haven't used them as a redemption, so they were floating in my account, without being used.
Your case is a bit different, though.
Think that phoning them up, is the best policy, pay the points penalty, at least maybe get some of the points back, if you cancel, rather than do a no show, no contact.