This is a question that only you should decide.Some traders have a system in place that they will only let a particular trade go against them so far. Based on a % or a figure. If you have a system then I understand it is best to stick with it. Don't get emotional, don't fall in love and don't hold grudges against a stock.
The question is when to take profit or when to take a loss.
Profit
Some like to take a quick % and move on.
Others like to pick a stock they think will better than double then sell 1/2 of the shares at that time. This allows them to hold 1/2 the shares at NO COST. Then they will decide at a later time what to do with the free shares.
Loss
This is the hard part for me. I have a hard time admitting I was wrong. When I sell at a loss - in my mind I am saying "Paul, you were wrong". Get over that feeling if you can. This is where a system come in. Even if you take a loss, you can feel a small amount of victory because you held true to your system.
Summary...
You got to answer it yourself, and pick an answer you can live with.
I sold IBZT a whil back for a little under 1 cent. I can beat myself up for not holding it longer. OR I can fell that I made the sale at the point I decided and did not let greed get the best of me.
LOSS vs. GAIN
FEAR vs. GREED
Welcome to the market.