A friend gave me a plant he kept small because he wanted to have it ready when his smaller plants were ready. He did little nutes and the light was far away since it was with seedings. At one month it looked almost identical to yours. He gave it to me, I added nutes to the AG, took off some of the lower leaves that were dead and now in 2 days it grew 2 inches. Might be your nutes are low, if the plant is growing like it should, you should be having to add a few cups to a 1/2 gallon of water to the AG each day, they can suck up alot of water.
Add a fishtank air pump to the aerogarden. It does make a big difference in how the plants react and the plant loves the extra oxygen, just a single fishtank airpump(they are cheap, about $

and a airstone, nothing special. If you can I would also add 2 CFL bulbs 2700k, most bright white ones in store that cost about $1-$2 are 2700k and does make a difference. 2 23 watt bulbs is all you should need, and you can pick up some cheap shop light reflectors to put them in.
I use general hydroponics nutes, 15 ml per gallon of the bloom/10 ml for micro/5ml grow now that it is in full bloom, but I used 3/4 of that when in veg and in the AG. There is another possiblility, the AG lights I have seen the paperwork say they lose their output at around 6 months old, so you may not be getting full output on the lights too. My AG came with a set of bulbs to replace at 6 months.
I also keep my AG lights about 1 to 2 inches from the top of the plants, as close as I can get without them touching.
when I did my last AG veg, I on purpose kept the plants low and bushy, maybe too much, but I like the results and looks like it may be a nice harvest, I still use CFL lights on the sides of the plants in the grow tent.
I am a little paranoid of root rot, is the reason I use hydrogen peroxide, I was given a 2 week old clone in my last AG grow and the plant got root rot, brown and slime all over the roots, so after that I had to throw the plant out, so I use it for more of a percaution than anything else. I also use a Canna cannazyn, a enzym supplement that breaks down any roots that have died to prevent any root rot. The main reason I am doing this, is in the AG the roots tend to get bunched together, when I put them in the grow tent to flower, the roots were so pakced they started to brown and I was worried, once I added the cannazym and hydrogen peroxide the roots took off again and now are huge, so I am just going with what worked, plus I have read that hydrogen peroxide is good to give oxygen to the roots. The superthrive, isn't anything much, some say it is snake oil, others swear by it. I feel the plant is doing very very good and is my first time ever growing anything really, so I am just using what has worked for me. I had alot of issues in my grow and now I feel I worked most of them out, so just passing on some advice. I am doing my plant now with fully submerged roots and I have a greater chance of it, so being safe. I am using botanticare Sweet now in the AG and the flowering plant, not sure if it is doing anything, but wasn't expensive, so going to try it. I stopped using the superthrive in the bloom stage since I read places it is best to use in veg only.
Good luck, your plants look like they can recover, just have to figure out if it's ph, nuts low or low light output.