I\'m writing an ASP.NET Core app (on the full .NET Framework) that uses WebListener, rather than Kestrel.¹ I\'m using Visual Studio 2015 with Update 3, and \".NET Core 1.0.1
So we've been struggling with this as well. What we ended up doing was having a copy of the launchsettings.json which was "clean", without the IIS Express stuff in it, and then having a pre build script which copies the clean version on top of the existing version.
Create a new file. launchSettings.json.pristine in the same folder as your existing launch settings file.
Add a pre build script to copy the clean file overwritting the IIS settings.
cd ..\..\..\Properties copy launchSettings.json.pristine launchSettings.json
This should effectively copy it over on build/run/etc.