Yes, in ExcelLink you can define if you want the info to be imported to a new row every time it accesses data in the PLC. It can also be defined to overwrite old data after some amount (e.g. after 1000 data points) have been received.
If your PLC is attached to a PC by RS232 port, you can also make the PLC open a file on the PC and append data to it. There is no limit of how many lines you can append to the file. You can also create different file names (say based on date) so that you can save all the data of a particular day to a particular file.
For more details, please read "File and Email Services".