Reliant Battleship shield?

BS-class ships do not have the option to mount a shield separatly.
Once you buy a BS you have a "fixed" shield on it, which you will not loose.
Your BS should stil have the shield, which should be visible for you again (blue bar, in space) once you have docked and repaired your ship.

Loosing a BS's shield only happened in the times OP fixed the BSes in 1.8x, and I suppose again with 1.9's arrival(if it worked at all in SP).

Anyway if you have no shield, the only way to fix it is rebuying the BS, or try another.

are you in your BS (the old one?)?
If you can launch without having bought anything and without having rebought the BS try to trade your current BS into a different ship (Fighter class) from a different station.
If that works, then you should be able to buy the BS again, without getting kicked when trying to launch to space.

Hope it helps you

Right, when BSes were fixed (the first time did was like 1 year ago after 1.81) you had to rebuy it, but right now 2 other fixes passed, for the last one you have to:

Buy fighter, exit the server, enter and buy the BS you choose, but choose carefully there are new and very cool battleships arround as well Maybe you don't have much money for buy/rebuying.

You can store your BS guns into another char, or tell somebody to keep them for a moment, while you do the rebuying, it's not needed to sell them.

rebuying battleships does not work... you have to buy a different ship and then buy the battleship again -> stupid FL anticheat