In fact, if the Bitcoin price drops, the DCA amount we use should be higher. For long-term Bitcoin investors, a price drop isn't a problem it's actually a good opportunity to buy more Bitcoin. So, you don't need to fear a Bitcoin price drop.
I don't think the amount you invest in bitcoin should be based on how far the dip goes. That may show a lack of planning, and it's not advisable to just make decisions based on how the tide goes, especially financial decisions. If you've originally planned it that you're going to put in a bit more money if the price falls lower than expected, then that's fine, but doing it spontaneously is not a good look in my opinion, except you have a lot of money to spare.
You might actually regret it if you get too greedy because there may be other stuff to do with the money, and then you will put yourself in a tight spot. With DCA, you will keep accumulating as long as bitcoin is dipping, so no need to do more than you can.