Simple answer: NO
Look at the above diagram. Going from memory, a winch and bumper center their weight about 24" forward of the front axle centerline. If your rig had 2000 lbs of sprung weight front and 1600 rear, adding 150lbs of winch and bumper would leverage an additional 190 lbs on the front axle and remove 40 lbs from the rear axle.
Since you already have a heavy bumper, you're effectively only adding the weight of the winch, ~ 80lbs, so the net effect on the front axle is about 95 lbs additional load. Divide that by 2 and that is only 47.5lbs additional per spring. If your springs were linear rate, they are probably 200lb/in or higher. that means that your front end would settle 1/4" or less with the addition of the winch.
Conclusion: Do nothing, a 1/4" is not very noticeable.
Now if you want to get more technical, 150lbs of additional weight hanging 24 inches out front would leverage ~190lbs of extra weight on the front axle. To properly compensate for this, you actually want a spring with ~10% higher rate to keep your ride frequency the same. A taller spring will make the truck sit properly, but ride rate will still drop and the truck will feel more "bouncy" and "rolly".
Most people aren't going to notice and again, given that you are really only adding the weight of the winch, I would leave the springs alone for now.