[...] how important it is to share our appreciation for others while they are still alive to hear it.
#33,703In this context, Copyright is correct; the meaning is "with it" or "in the know."
There are helpful online reference for American English usages that don't necessarily appear in older dictionaries; look for "slang dictionary" in search engines.
Parla, Sep 23, 2010
"So you like this place? Anything in particular?"
"Well, I was floored by the professionalism of the people."
Parla, May 26, 2016
I'm late to this thread by several years: It's because I have bursts of activity on WR with long gaps in between. I certainly remember Parla because of the clarity of her answers. Her contribution made so much difference and still does through the medium of the WR dictionary where users can search for words and phrases that have been discussed before. I'm sure her contributions in many other areas of life are just as well remembered.