Thanks for the question Clipse,
This is known as scaling in. Basically it's adding to or building into a position. The opposite of it is called scaling out - cutting your position as time unfolds. Just like everything else, I'd recommend that you systematically test the concept and be sure that you are accounting for risk at every step. After all, if you scale into a long position, you are increasing the average entry price of your trade, meaning that you could turn a winning trade into a loser.
For example, if you buy 100 BTC at $1, your average price is $1.00 per BTC. The price goes up to $2 and you buy 100 more BTC. Your average price is now $1.50. Let's say price reverses and your exit signal occurs at $1.25 - you lost on this trade.
Here's some general and specific recommendations. Let's start with specific. Prior to entering a trade, if you are planning on scaling in, you should select a criteria which designates location as well as the amount you will scale in. A very specific criteria I suggest is using the Average True Range (ATR) indicator to determine locations to scale in. I use multiples of it at the time I enter a trade to determine scale in locations. I use the 14 period ATR for this. Period doesn't particularly matter, it should just make sense.
Example trade and scale-in:
-You enter the trade long at $3.06 and the ATR at time of the trade is $.26
-Scale in Location 1: Close + 2 * ATR = $3.58
-Scale in Location 2: Close + 4 * ATR = $4.10
-Scale in Location 3: Close + 6 * ATR = $4.62
-Scale in Location 4: Close + 8 * ATR = $5.14
--When price reaches these locations and you have an existing trade, you will buy / short another trade unit. I suggest that this unit be equivalent or less than your initial size in the trade.
--For short trades, subtract the ATR value
General recommendation - every time price clears a prior retracement in the direction of the trend, then you can add to the position. This is very subjective however and more vulnerable to emotional decision making.
I suggest not scaling more than 4 times. The idea of scaling is that if the market strongly moves in a direction, you will be in it with progressively more capital. If the market doesn't move very strongly, however, you will find that you have a higher percentage of losing trades.