There is no faster way to do this.
Edit > Manage Results > Reimport
is the recommended thing to do after adding new molecules, or changing settings that might affect chromatogram extraction.
Skyline extracts chromatograms by reading every spectrum from the beginning of the run to the end of the run, and extracting chromatograms for all of the targets in your document. A lot of effort has gone into making that go as fast possible, and we have not implemented any sort of optimizations for cases where only a subset of the document needs to have chromatograms extracted.