Dependency injection for extension classes?

I'm using Microsoft Unity as my IoC container. I have a number of extension classes which adds useful methods to my business objects This is the sort of code I use today:

public static class BusinessObjectExtensions
{
    public static bool CanDoStuff(this BusinessObject obj) 
    {
        var repository = BusinessHost.Resolver.Resolve<IRepository>();
        var args = new EArgument { Name = obj.Name };
        return repository.AMethod(obj.UserName, args);
    }
}

Is there a better way to manage dependency injection for extension classes?