I went from a D200 > D300 (stolen) > D300S and found the D300/S to be better in every way to the D200. That was 5+ years ago, and technology has moved on. You get a better sensor with the D7100, and the ISO and Dynamic range advantages that have evolved.
Saying that, there are some ways in which the D300S hasn't been surpassed by the D7*** range, and arguably by any APS-C camera yet. If for some reason I didn't have the D300S I would try to get another D300S because I like to take pics of a bit of everything and the D300S is the best camera for that imho. A 7D could fit the bill (at a pinch) as well if my lenses were to go as well.
But if you want a high frame rate the D7100 has had the buffer crippled for some reason, and that added to the slightly slower frame rate, and the D300S is still better. (for me) It depends on what your priorities are, never shoot high frame rates and that is not as big a consideration. A D7200 may address those issues, but then there may also be a 7DII which should be better than the D7200 unless Nikon really update the specs of that. And there is speculation that if Canon release a 7DII, Nikon may release a D400.
Would a new camera give you something you are really missing now? With what is available now, I would get a D300S, but try a D7100 to see if it is something you could live with, as some can't live with the compromises. If you can wait, see what a D7200 turns out to be, but as a D300S owner waiting for Nikon to deliver a D400, (probably never happen) some of Nikon's decisions can't be predicted, so waiting for anything could be a mistake.
