This is going to sound radical, but in my opinion, not monkeying with your ATF is a good thing. ATF is much more critical to AT performance than simply being a lubricant. Besides lubrication effects, it is a critical hydraulic fluid in multiple places in the system. It has to work correctly in all of them (line pressure in valve bodies, as a friction component between discs, energy transfer medium in the TC vanes, etc.)
I have had good success with Lubegard products (I have the blue biotech in the engine oil in one car now). BUT, I would use the red in an AT with great caution.
It has a MFT of friction modifiers in it. If your fluid is worn out, it will replinish them. But if the fluid is old and sheared, it won't alter the viscosity, which also has A LOT to do with shift characteristics. (This is why Dex VI works poorly in some DexII/DexIII designed transmissions, for example - despite what GM says) If you have a PWM torque converter (most cars after 2000 do), it can thus delay the lock-up and generate more heat in the TC, despite the product claims.
IMO, the sounder policy is to swap out all the fluid and just put fresh, correct fluid into the unit instead of trying to doctor the worn fluid, or to try to doctor the fresh fluid and shift it outside the boundaries the transmission was designed around. Radical thinking, I know.