I would wait until your seedlings have bloomed for this year and then compare this seedling with others from the same cross or from similar crosses. Then choose the best seedlings from the entire year's crop. You might decide to keep 10% of the seedlings or 25% or 1% or whatever you feel you should keep. Then if it is still one of the keepers you might need to remind yourself what made you cross Blueberry Lemonade with Pure and Simple. In other words, what were you hoping to change and how.
As an imaginary example, perhaps I might like Blueberry Lemonade but want it to be taller (or shorter). Or perhaps I like it but want to put the eye pattern on an orange background rather than a yellow background, and so on. That might help me choose what I would cross the seedling with to get closer to my goal.
Daylily flower colours become "muddy" when the yellow-orange pigments (carotenoids) are increased in the presence of the purplish pigments (anthocyanins). 'Blueberry Lemonade' (BL) presumably has less of the yellow pigments while 'Pure and Simple' (PaS) has more. The seedling has an intermediate amount and presumably more than BL. At the same time the seedling would have less of the purplish pigments in the eyezone., but has gained some amount of them in the rest of the petal.
To make a 'muddy' colour clearer the suggestion is usually made to cross it with a 'clarifier'. Clarifying colours in daylilies are near-whites, some pale creams or very light yellows, light lavenders and perhaps some very light pinks. The idea is to reduce the average amount of the yellowish carotenoid pigments in the seedlings and thus reduce the muddying (brown) effect. If you cross the seedling with say a near-white then the base yellow colour of the petals should be lightened in the seedlings, as one might also expect the base anthocyanin colour of the petals to also lighten. If you cross the seedling with a near-white with an eyezone then the seedlings should have a darker eyezone but lighter base petal colour.
Because daylilies are outcrossing all the suggested results of crosses are guesses of the average results and the seedlings can vary enormously. We might not have guessed that a cross to PaS, which does not appear to have any anthocyanin pigments would produce seedlings with anthocyanin pigments outside of the eyezone, but it did. There can be many such surprises in daylily crosses.