Sprite is a pretty die hard plant so lots of room for trial and error! What type of substrate do you have? I have a high light tank with C02 with sand, and when I try snipping and replanting I think the sand suffocates the stem(turns black and breaks off above the black part)and it ends up floating after a few days... I also have a med light tank which I dose C02 Booster with Eco-Complete and those stems slowly form roots and take hold! Now in my high light tank if I trim a piece that I want to replant, I rubber band it to a small polished rock an place it where I will be planting. After a few days the roots start forming and I remove the rock and bury the roots 1/2 above, 1/2 below the substrate and it stays in place. I have also found that the pieces I have let float to form new roots, tend to grow out more like a bush( cause they grow to gather as much light as possible and floating they're pretty close to my light) rather than growing tall like I want them to...
Also, be sure and trim off any "branches" that turn yellow and the leaves start to flatten out. I've read this means the plant has consumed its max amount of nitrates, and if left alone will break down and release the nitrates back to the water column. I use PPS Pro dosing and when I started I did what you said and was dosing nitrates daily and was at 40-60 ppm! All my sprite was turning yellow. Now I dose potassium Nitrate once after a WC, then test for nitrates and dose accordingly to keep the level in line of 10-20ppm, and that keeps the leaves, that beautiful light green! Hope this helps, good luck!