Yes, in most cases exiting and then reentering is preferred.
However, that, like many of the bromides here is easier said than done.
I refer to the notion that once you are in a trade that has gone against you, that it's sacrilege to add to the position at some later point.
This is a toxic premise. Each trade is a separate event, standing alone, within the confines of a total risk management scheme. You would not want to add endlessly to the same trade so that your account was at risk.