I guess if you are trying to avoid using your computer, you could move your files back to your phone, then put in your new card and move the files onto your new card.
Whne you place the new card into the phone, you must format (Options, Media Card, press Menu, Format) it in the phone. This creates the folder structure required by the BlackBerry. If you format on the PC, this structure will not be created.
With the Media Card installed, goto Options, Media Card and set Media Card Support: On
Encryption Mode: None - unless you are paranoid
Mass Storage Mode Support: On
Auto Enable Mass Storage Mode When Connected: Prompt
Now when you connect your phone to the PC (provided DM is installed). The phone will prompt you to enable Mass Storage Mode. Select Yes and the Media Card will show up in My Computer as a new disk and then you can Drag 'n Drop your files to the correct places on the Media Card.
Desktop Manager must be installed on your PC and should be able to display your PIN number at bottom left of the DM panel when the phone is connected. This test confirms good working of the USB interface with the phone.
Desktop Manager MUST NOT be running for Mass Storage Mode to work or to be used.