OS X - AppleScript Question about moving files daily to another folder (folders vary)
If I understand your requirements correctly, then this script should do what you want. Make sure to change the username on the first line to your username.

set username to "lizzan"

set cy to (year of (current date)) as integer
set cm to (month of (current date)) as integer
set cd to (day of (current date)) as integer

set yd to yesterday(cy, cm, cd)

set yy to item 1 of yd
set ym to item 2 of yd
set yd to item 3 of yd


set yFolder to "Macintosh HD:Users:" &amp; username &amp; ":Documents:To Do:" &amp; yy &amp; ":" &amp; ym &amp; ":" &amp; yd
set cFolder to "Macintosh HD:Users:" &amp; username &amp; ":Documents:To Do:" &amp; cy &amp; ":" &amp; cm &amp; ":" &amp; cd

tell application "Finder"
    move every file of folder yFolder to cFolder
end tell

on yesterday(y, m, d)
    set d to d - 1

    if d ≤ 0 then
        set m to m - 1
        if m ≤ 0 then
            set y to y - 1
            set m to 12
        end if
        set thirtyones to {1, 3, 5, 7, 8, 10, 12}
        set thirties to {4, 6, 9, 11}
        if m is in thirtyones then
            set d to 31
        else if m is in thirties then
            set d to 30
        else if leapyear(y) then
            set d to 29
        else
            set d to 28
        end if

    end if

    set yd to {y, m, d}
    return yd

end yesterday

on leapyear(y)
    if y mod 4 is 0 then
        if y mod 100 is 0 then
            if y mod 400 is 0 then
                return true
            end if
            return false
        end if
        return true
    end if

    return false

end leapyear


Caveat: The script will fail (and have moved possibly only some of your files) if there is already a file with the same name in the folder it is moving to. If you want to replace the files in that case, and avoid failing, add with replacing at the end of line 18 (move every ... to cFolder with replacing).

Edit to add: Oh, just saw that you had it set up in your Dropbox instead of in the Documents folder. Just change the paths on lines 14 and 15 to reflect the path you're using, and it should be fine.