Start your search where you were last catching them during the early ice period (off the drop-offs, and mid-depth weeds). If the base of the drop-off is deep enough, Panfish will stay here for the remainder of the winter. If there are no Perch on the base of the drop-offs, it is safe to bet that they moved to off shore mid-lake structure. These structures include humps, grass beds on flats, or really anything that is a change from the surrounding area (like a fallen car).
One trick professionals use, is to look for micro transitions. These transitions can be small changes in depth along a flat, or a change in bottom composition (hard bottom, to soft bottom change).
If you are fishing break-lines, look at a contour map and find anything that is a change from the ordinary. These changes can include inside turns, points or even a steep drop-off beside a slow tapering drop off.
Why Panfish move to the deeper waters because the shallows are lacking oxygen and are much colder. Deeper water is usually warmer and provides much more oxygen for the fish.
Tactic When ice fishing for any fish, it always comes down to Location, Location, Location. It is important to drill a ton of holes, and only setup at a whole if you are marking fish on a sonar. Use a heavy jig (Tungsten) that can get down to the fish fast, that way you don’t waste any time.
Once you find the fish, you can slow down your presentation and fine tune it (colors, weight, bait choice) until you find what the fish want. Keep changing until you have a successful pattern.