Here's a great tutorial about bearings that I reference often. I'm not familiar with the Shimano Citica but I've just removed the seals on 16 bearings, cleaned them out with CRC Brakleen brake parts cleaner, dried them out with canned air and re-lubed them with Corrosion X per Alan Tani's tutorial. Since all the bearings had a retaining ring holding the seals in place, it was easy to remove them and re-install both the shields and retaining rings after cleaning and re-lubing them. Not all bearings have a retaining ring however. If you want to clean and re-lube those that don't, you have to puncture the seal being careful not to damage the bearings under the seal, then replace them open, without a seal. Some bearings use oil, some grease. As a general rule, spool bearings use oil, all others use grease. This tutorial says Shimano uses open bearings packed with grease.
http://alantani.com/index.php?topic=13.0
Here's a tutorial on the Citaca 200e, hope it helps
Alan Tani is THE GURU
http://alantani.com/index.php?topic=3200.0