Nate, I think you need to create a macro within which you use search and
replace (ctrl-H).
The usefulness of this approach will depend on the degree to which the text
within each cell (that you want to modify) has repeating text strings that
are uniformly located within the cell.
Otherwise, you can skip the search and replace idea and write your macro so
as to proceed from cell 1 in row 1 to, say, cell 3. Then press "end" to
position cursor at end of text in the cell. Then enter the text you want to
add. Then position the cursor in cell 1 in row 2. Attach the macro to a
keyboard combo and you can repeat this process much more rapidly than
resorting to manual editing.
No joy if the text is not always to be added to the same cell in the row or
if it's not always added to end of the text already in the cell.
It's not possible to tell from your request what the structure and conent of
your tables are so it's hard to be more specific.
Richard