Regenerate NuGet repositories.config manually

Question

Is there a way how to manually regenerate NuGet repositories.config for a particular solution?

Edit:

Updating any package explicitly to the same version will eventually regenerate repositories.config, but will update the package configurations in every project within the solution as well. I am looking for a cleaner way how to do this.

For instance, when having Newtonsoft.Json version 6.0.8 and "updating" explicitly with Update-Package Newtonsoft.Json -Version 6.0.8.