If you are talking about replacing the brake fluid, you will need to replace all the old fluid if there is water contamination. Syringe out all the old fluid from the master cylinder and replace it with fresh fluid. Then bleed all the wheel cylinders until fresh fluid comes out. Since the new fluid is probably also now contaminated with some water (any contamination is bad), I would repeat the process - replace all the fluid in the master cylinder with fresh fluid and bleed the wheel cylinders again to flush the lines.
For the problem of a bouncy ride, it sounds like you need new struts.