I own LMND dec17'21 50 call
I bought it for $30 now it is $24
So I am losing $600
I would like to keep long position in this stock but not sure how to figure out when to sell it and buy a new option with a dif.exp date and strike price.
thank you
Thanks for your answers, I am just going to take the risk of making a fool of myself by saying you are quite new to options and did a pure directional bet on the underlying hoping that your directional bet would pay off and you wouldn't need to fork out the full amount for buying the underlying but instead you know about deltas and the effect of the underlying on the option prices via this delta mechanism so you thought I will buy the deep ITM options to gain from my believe that the underlying will increase.
So, now if your premise is that the underlying will increase in price still now (for all what its worth we don't even know if your losses on the options have been an effect of the underlying going down, or you have lost on theta or the Vega taking a hit since you bought those options) point being there are so many ways losing money on a long option than there is to "win".
So unless you don't grasp those aspects and you are anyway making directional bets, then take your losses for now, and go buy the underlying if you still believe in it going up, at least in that scenario you would not have to deal with the underlying going up but the market lowering the ImpVol and putting your option position in larger losses all the way to expiry and locking your capital just to hand you merely intrinsic value and no time value.
Or take the advice of some other posters here by turning it into a spread and have the market pay for some of your paid premiums but also share your profits with the market above the short strike

... Whatever you do don't pay a hack, guru, mentor hard earned monies to teach you something you can pick up about options by online search or in a good book about the topic, for the technical concepts and trading I recommend Sheldon Nathanberg, if you are theoretical and mathematical and inclined towards that, then let me know and I can share a few of those references as well

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Happy trading and stay safe when out and about in the markets!