Water cooling in a rackmount case

My current build uses a H100i on a LGA1155 for a demi-water-cooled setup.

I've never done a full fledged setup water setup, but I understand the process and the theory. My main question relates to the case type I'm using. I have a 4U rackmount server chassis case, and it's not exactly easy to get into and out of. (Think about unscrewing 4 screws which attach a >50lb steel case to a rackmount and hoisting the thing out and onto a surface, solely by the steel handles in front.)

This being the case, I have a couple questions. Are there pump/reservoir combos which would allow me to leave the unit installed and still be able to change out the fluid? Also, how often should I change out my fluid?

luckily changing fluids is one of the things that you least need to do.
most people will recommend every 6 months only, and I have been on water for 9 months, since my last change, and having very very minimum fluid loss. in a close system, you shouldn't have to change often.