What would you do in this situation?

I've curious as to other people's opinions & input. My grandmother recently ped & left me an small inheritance which I diversified while investing some went to bonds & other stocks while some stayed in the bank. One of the stocks though did suprisingly well & more then double in about a month. I've always been a long term focused person but the thought has crossed my mind about cashing in some of the profit from it while keeping the orginal investment & investing the money in other stocks cheaper in price but with solid history & strong future outlook. I haven't decided but was wonder what other people thought or would do? I have no debt so I don't need to worry about money right now which is why if I cash in if either the new or orginal investment suddenly tanked I wouldnt really care.