RMS Detail Analysis, page-145

No you don’t lose your position in the market depth if you increase your order.
The additional amount goes to the bottom of the market depth, but your original number remains where it is.
I often take advantage of this by using the same buy or sell order to trade without incurring more brokerage.
For example as my order gets to the top of the queue, I’ll often add 1 or 100 shares to the order so that my order doesn’t get completely filled. When the first lost fills, I then adjust the bid or offer price to use as a free trade at a later date.
I assume other people do this too. Its one of the reasons you’ll often see small volume amounts in the market depth. (the 1 share at the end of 14.5 cents sell depth is one of mine as I have a larger order higher up in the queue , as is the 1 share at 11.5 cents).
Over the last few weeks I’ve been able to buy and sell RMS half a dozen times without incurring any brokerage using my unfilled open orders. Just need to be patient sometimes.