Copy Data From Previous Row Into New Row IF Userform Textboxes Not Populated

I have designed a simple user form to populate a finding tracker spreadsheet. Updating the tracker works fine.

Although I only need to update certain textboxes in the user form, I find myself having to enter the same data in every textbox so that the next row of the spreadsheet is filled. In all cases, if a textbox is not updated for the next row, then the data should copy the data from the previous row.

For example, last data Transferred from the user form are as follows:

[Heading] Col A - Col B - Col C
[Row 1] Apple - Red - 10

Assuming I would only update the textbox for Col C in the user form, the next row in my spreadsheet would look like this:

[Heading] Col A - Col B - Col C
[Row 1} Apple - Red - 10
[Row 2] (empty) - (empty) - 20

As such, I would like to add a code that allows the data (Apple and Red in Col A and Col B) from the previous row to be copied automatically and only updates Col C with the new value 20.

Oh, I should add that I have mostly Textbox values (about 20 columns) in the spreadsheet with the exception of three columns with CheckBox values although I can always repeat the checkbox fields.