As per my knowledge, once UE detects RLF, it attempts to recover the radio connection by using RRC connection re-establishment procedure. Before initiating the re-establishment request message, UE goes through cell search and other basic procedures. It sends re-establishment request message to the selected cell that can be any cell (PCell or SCell or any new cell). If eNodeB finds the UE context then it handles the request else send re-establishment reject.
Application layer running at eNodeB can manage many cells. It is specific to vendor implementation also.