The word "trope" didn't originally apply to stock characters/plot elements in the way that it is now used in TV Tropes; this is a relatively new (as in past 50 years) usage of the word. This may be why dictionaries come up short: even some English dictionaries I checked didn't cover this meaning.
There is a Japanese wikipedia page for TV tropes, which uses the word トロープ, but this doesn't seem to be a widely used term and the writer of the article felt the need to explain it rather than just giving simple translation:
Various conventions and ideas seen in works of fiction.
So I don't think you will find a single word to cover this. お決まり (and お定まり?) may work for "cliche" in some situations (お決まりの台詞, お決まりのパターン) although they're not limited to fiction. Wikipedia uses 類型 for categorising some things, e.g. ストーリー類型, but again this appears to be a phrase coined for convenience and not widely used in general discussion.
There are some words that will cover some of the things covered by "trope". One (relatively recently coined and probably more an internet slang term than something for academic discussion) is フラグ. I'll quote from wiki again as I think this covers it:
Although it has the same meaning as 'foreshadowing', 'flag' implies a relatively simple, fixed, "stereotypical pattern".
There are various types of flag (e.g. "death flag", 死亡フラグ). For more description of this term, check dic.nicovideo.jp/ for フラグ and other terms. This site also probably functions as the closest thing to tvtropes in that although it wasn't created for that purpose, if you look up various manga/anime you will find often find links to character types/phrases/story genres associated with that work.
Another useful word is from 落語 originally and is 落ち (when dealing with manga/anime, normally written オチ). There were various set ways of ending a story. A classic one is まわり落ち (ending by returning to the beginning of the story), and 夢オチ is the Japanese name for the "and then he realised it had all been a dream" ending.
The last one is 定番, often in the form (genre name/series)の定番. These are both 2ch examples:
やめてほしいアニメの定番 ("anime staples you want to stop")
ＲＰＧの定番モンスターの名前を貼っていくスレ ("thread where we post names of typical RPG monsters")
Not necessarily negative, it can also be used to refer to classic/staple/standard examples of a genre, e.g. 定番のクリスマスソング (typical Christmas songs).