I've been a .NET developer for going on 12 years and I'm still as passionate today as I was on day one.
If you're stuck witting console apps and don't have much variety in your development work this can be difficult. I think I would probably feel the same as you in this position.
The thing that has kept .NET interesting for me is learning all the new technologies built on top of the CLR - recently MVC, WebAPI, EF, Azure, etc.
To work on technologies you find exciting I would suggest the following:-
Learn other areas of .NET that interest you in your own time and be an advocate for using these technologies within your company. Show your boss the benefits of technology X over technology Y and how it would improve his / her bottom line. Show how it would save you time in development or allow you to scale more easily.
If this is not an option consider creating a software product or API that would help you with something in your daily life using a technology you find interesting. This is a great way to learn a new technology and who knows it may lead to a new business or product your company could use internally. You also then get the opportunity to work on something your passionate about and use the technologies that excites you the most - two birds - one stone.
If you're not passionate about .NET development anymore maybe consider pivoting your skills. For example would you find front-end web development more interesting? This moves along at a quicker pace then .NET development and I know creating visual experiences rather than back-end plumbing code can be more rewarding at times.
Best of luck with whatever you decide to do.