Seriously, check out the "straw modification" for your carts. You won 't believe the difference it makes! I could never get more than 2-3 drops after the atty started to dry out. Once I did the straw mod, it takes longer between topping off and I put in 8-10 drops topping off now! (Basically, a refill - no more topping off needed!)
It's really easy to do - just cut a coffee stir/straw to just under the length of the inside of the cart. Cut one end on the diagonal, cut off a little off the filler (you won't need as much now) put the straw in angle side down, put the filler in next to it (it should sit lower than the straw) and fill it up with liquid! (There's a bunch of videos on how to do it, too.)
I don't need to top off or drip anymore!
You could also try the Lipton Pyramid Tea bag modification, too.