I would take everything apart, clean and sanitize. I wouldn't replace anything unless it's needed, except maybe get some check valves for your manifold. Just soak the lines and manifold in water, then rinse in some Starsan. There's probably not any dried up gunk in there. If so, then replace what's necessary and scrub what you can.
Good price on check valves:
http://www.ritebrew.com/product-p/843680.htm
All of my system is put together with swivel nuts, so is easier to disassemble than a system with barbed connections. Not sure what your system entails.
I believe keeping everything clean is always good practice. I have a bit of OCD though, so take that into account.