Definitely do not give up hope. Citrus are amazingly resilient. The roots are trying to recover. The leaf drop is from a combination of damaged roots and transplant shock, completely expected, and the damage, frankly, was probably done prior to your repotting, even, and you're now just seeing the fruition of the damage. Stressed trees are targets for bug infestations, so treat, treat, treat. Spider mites are very persistent, and if you have other houseplants, you'll have to treat those as well. I would first off, take your plant outside if the day is warm enough and hose it off with a hard spray of water, to knock off as many spider mites as possible. If you can't go outside, take it into the shower and hose it down. Treat. Repeat this process at least 6 times, about once or twice a week. Continue to lightly fertilize until you see new flush. Once you see new flush, you can increase the strength to 1/2 strength. Provide more light if possible. And just for future reference - you want to try to pot your tree up higher in the pot, than so far down. Not really enough room for root growth having it so deeply potted. Patty S.

Is it possible to have a fungus gnat larvae infestation but never to see an adult fungus gnat (over a period of several months)?

I have washed my tree, it took awhile :) Now i'm bringing it outside for a few sunny hours a day and hope that the leaves will start looking better soon! I took off whatever was in my trunk, it was like a light colored jelly covered by dirt..washed it and gently scraped the rest off with a shape knife. Does anyone know what that is? Irina

Your tree looks lovely. How your plant will respond to your repotting will depend on what you do. If you bare root it into a completely different medium like 511, it may go into shock. If you just upgrade it into a larger pot, lightly loosen the roots and add fresh growing medium, I don't think your tree will drop too many fruits. Maybe none because your tree will be happier. It may even drop some fruit naturally in the future because it can't support them all. Fruit drop may occur when you put it outside and something triggers it to drop some more for whatever reason. Meyers bloom all year if the growing conditions are right. If you lose a few with the repotting, you may get more blooms later after it settles down. Don't put so much emphasis on keeping the fruit, but rather on the health of the tree. I would repot it now and let it settle into its new environment. Spring is almost here and soon you will put it outside. New blossoms will be sure to be forthcoming then. I repotted my 15 year old Meyer lemon 2 weeks ago. It was severely root bound and blooming as well. I pruned 2" of roots off the bottom and even removed some around the sides. It has shown no adverse side effects. I admit that I live in middle GA and did this when we had a 2 week warm spell. I have also been taking my tree in and out of the house for some sun and fresh air since the repotting.