If you turn $15 into $400, then just keep doing what you are doing...
be patient. If you are a winning disciplined and patient player then the money will take care of itself.
This whole thread/query reminds me of a popular joke.
There are two bulls, one young and one old, on top of a hill overlooking a field of cows.
The young bull turns to the older bull and says, "Hey, I got a great idea, lets run down the hill, screw a cow, ,and then run back up the hill..."
The old bull replies, "I got a better idea, how about we just walk down the hill and screw them all..."
Noobs always remind me of the young bull, full of energy and super impatient and just can't wait to get their bankrolls up to $1k, $2k, $10k, etc...
But the problem is that eventually their impatience results in them making mistakes and losing more money long term. And if they would have just been patient and disciplined everything would have worked itself out for the best.
So just follow proper BRM, be patient and disciplined and your roll with take care of itself.