Great job getting it through your first winter!
Since it's in a north-facing side of your home, this may be why it isn't doing so great. The north side in the northern hemisphere will keep your tree in perpetual shadow -- if it is in fact kept near your home.
I would aim for a south-facing side of the home if at all possible. If you cannot, try for a southwest, or even southeast. If not, then west or east -- anywhere other than in the north.
Depending on your substrate (soil) used will determine how much water it's holding. Your watering needs will be different from someone else with the same specie but potted in a different substrate blend. Given that you've kept it in the north, I'd say that's also allowed you to water less frequently due to reduced evaporation.
Try and move your bonsai, the ficus and juniper too, to a better position so they can get some full sun. Be prepared for your substrate to dry out quicker due to this change. It should require you to water roughly once a day, but again, the soil that your trees are in can greatly affect how much water they will need -- so only water when they need it. You'll adjust to your new watering schedule in no time.
Also, try to let the substrate dry out a bit -- just to where the substrate is just slightly dry but not all the way (feeling about an inch deep) and then water again. Ensure that when you're watering, that you give it a good soak, though gently, with your hose or watering can. Allow the water to run clear from the bottom of the pot's holes, wait a few moments for it to drain, and then do this once more for good measure.
I would say you'll start seeing some improvement in about three weeks, if not sooner, after they are receiving the sunlight to produce more photosynthates (energy). Try giving that a go and checking out some videos on YouTube on bonsai care too. You may want to look into what a rootbound bonsai looks like, and then study on how to repot properly so you're prepared for the inevitable. If there aren't any signs of your trees being rootbound this season, try and shoot for repotting only when it needs it in the fall or in the spring (at the cusp of buds swelling).
Fertilizing might need mentioning, if you haven't yet. Typically, this is about once a month, though I don't personally fertilize in the summer. I'll start back up again and use a very mild liquid fertilizer in mid-August. But that's just me and you may want to do your own homework and come to your own conclusion. But be careful, your trees can develop root burn (chemical burn) from certain potencies. I personally use Dyna-Gro Bonsai Pro 7-9-5 during the spring, early and late summer, and into early fall.
Finally, if it were me, I'd let them recover from the lack of sunlight for the remainder of the growing season and forgo any sort of pruning or wiring to build up more strength, but again, that's just my two cents.
I hope this helps and hope to see some updates on your bonsai in the future!