I have found that to be the case. Refilling by topping off either with the same flavor or with a complementing flavor was ok, but just ok. I find that by removing the cap and the o ring, then holding under warm running water for about 30 seconds then blowing through the mouth end, then holding under for a few more seconds, blowing again, blowing onto a paper towel until no more water comes out, then tapping on the paper towel, drying off the battery connection end really well works great. Then just tip slightly and refill by letting the drops run down the side onto the filler and then rotating to get it to another place. I usually go 3 drops, turn, 3 drops, turn until the filler doesn't suck the juice up quickly - usually between 16 - 20 drops. Then I peek through the hole and make sure no fluid is in the hole, if there is, I blow out gently and dry the battery connection again. Then plop it on and vape. Takes about 2 minutes all in all, but vapes for hours with this method. Not as long as a new carto, but pretty well. Often I after a few hours I will top off about 10 drops without rinsing to refresh it.
Some people simply refill and have good success, but for some reason this method works best for me. I think you just kind of have to try different things and see which style works best for you.
