Refilling : New silica is packed in your HPLC column tubing. The column performance is as good as new column as the silca is new.  The new silica has properties/performance equivalent to Inertsil / Intsil.
Reprocessing: Under this process, the hplc column is emptied completely and same silica is repacked after treatment. The reprocessed column provides 60 to 100% life. The reprocess can reduce your column budget by 30%.