I'm using template haskell to include content from non-Haskell files in some of my code, and this content is then parsed and used. The problem that I have with using cabal as a build tool for this is that it doesn't detect when these files changes and so I find myself using cabal clean; cabal build which forces the whole project to be rebuilt (including some dependencies) which is slower than it could otherwise be.
Call Language.Haskell.TH.Syntax.addDependentFile, then wait for this cabal issue to get fixed.
As a workaround, you can add a comment to some relevant Haskell source file(s) to get them to rebuild (and re-execute their TH). Don't forget to delete it again next build and certainly before you check your source in!