Yes.

You must ensure you set up your combo box to use a "named" range, then you can modify it to become a "dynamic" named range.

For example, suppose your combo box has this as it's source:

First, select the range $A$1:$A$10, then put a name in the "Name Box" (upper left corner), like "picklist".

Then, go to the Data Validation dialog for the combo box and designate the source as:

Click "OK" (ensure the combo box is working with the named range).

Now, go to "Insert > Name > Define..." and select "picklist". In "Refers to..." change the reference to this formula:

then click "Add", then "OK".

Finally, check the results by adding an option to your list and see if it turns up in the combo box.

Cheers,