You can always quote yourself, or write it offhand and post it again without checking your old post.
You can, it's not only limited on the same thread, but you can re-use your old/same post in the other thread because there's no "self plagiarism" rule in this forum.
What I have noticed, even with well established members is that if they want to post what they have posted before they can just quote themselves. As easy as that.
Posting and reposting what you have posted before on this forum word for word is not making any sense in my opinion. Just quote yourself just as Beparanf commented already about it.