You can redo the leves you failed on your next leve reset. This should help ease the sting, as well as help any future players who fail their leves.

What happens is, when you fail, in your journal it will have a red "x" to note the failure. On your next leve reset, upon talking to any leve issuer, that failed leve will be AUTO-renewed (it auto-renews even before choosing new leves). If you exit out and look in your journal, you will notice the red x is gone and it will be "open" for you to redo. Now you can go back and redo-it, same reward as before.

Then you can now go back and choose your new leves, so effectively, you will be doing 9 leves on this cycle (so if you failed all 8 leves last cycle, you can do 16 leves total on the next cycle if you choose to do so). If you decide to select new leves before redoing your failed leve, be sure not to trade that leve for a new one.

I haven't done it after the 1.16 patch, but guessing it still works this way.