Sorry, Angella, I think that you will have to settle for me. Steve: may be thinking that you can sand the poly a little and put more stain right on the poly and when that is dry, another coat or 2 of poly. I don't think that will work because the bottom layer is stain is so varied in color that you will not be able to disguise it enough.
I think, from the sound of it, that you will have to strip the poly off with something like Citristrip, sand, brush down with a new brush and then wipe down really well with mineral spirits both to get the sanding dust and the oils from hands off of the wood, then go through the wood conditioner, stain, poly, sequence again. The stripper will not have much effect on the stain and you will end up with an overall darker color. If you don't stir the stain before you apply it, this might minimize some of the variation, or it could make it worse. Do one door, for instance, and see if the stain works better stirred or unstirred.
With any project this big, you might not have to take all the cabinets down, but you also might consider it. At the least, you do want to take the doors off and the drawers out and work on them in a garage, or basement if it has good ventilation. Be sure to follow all the instructions and safety minimums for the products that you use. The rags that you use for wiping the wood down with mineral spirits after the sanding should be pretty wet but not wringing wet. And don't leave them in the house, even for one night. Take them outside and leave them unfolded and not in a ball for a few days to dry completely or until you use them again.
Wear chemical resistant rubber gloves and eye protection as a minimum when doing anything with or near the finish stripper and keep kids and pets away. The neater and cleaner you do all this work, the less additional disasters you will have in your new house. We really don't want to answer questions like how you get a gallon of Minwax stain off your kitchen floor. The cheap, blue plastic tarps will offer some protection against disasters like this but you can't depend on them completely either.