In my view looking at one trade in isolation would be erroneous. The 29/- that you have received would be your profits at the time of booking it, but now it is your capital. IF you would have bought 2150CA irrespective of your profits on an earlier trade, then it would be a correct trade. But if you bought it because you made profit and would be losing nothing if it fails would be looking at it in a myopic manner.
All profits that you earn is your capital. Your evaluation of the next trade should be irrespective of the outcome of the earlier trade. Capital is capital, whether your initial or profits, it should be safeguarded in the same manner.
If your view differs from mine, I would respect that too.
My point is that by initiating such trades u dont have much to loose.
I have a SL of todays lows of the SBI 2150ca which is 13 or so.
There could be better hedges like selling a 2000CA where the OI is huge,
if i were to hold on to my initial trade of 2050ca. Such type of trades are helpful for beginners who like to allocate least amount of capital and restrict the no. of trades per expiry!