The reason you’re not passionate about your work is because something is missing. Identifying what is missing is your first step in determining where to go from here.
I have been in a similar situation. Always working. Important stuff. Sometimes cool, often not. But something was always missing.
Architecture not rigorous enough. Inadequate data base design. Insufficient requirements definition. Lousy code base. Unable to scale. Unable to expand or handle completely new features. But I always managed to make it work anyway. Then it occurred to me, if such mediocre systems were able to produce adequate results in commercial environments, what would be possible with great systems?
So now I’m building a framework/architecture/environment that beautifully handles everything I thought was missing before. The passion is built-in. Instead of, “Look at me, ma!” now it’s “Look at this, everybody!” Where do you go from here? Fill in the gaps that should have been providing passion all along. That oughta keep you busy for a while.