• Ctrl+H
• Find what: ^(?:\S+\h+){4}\S+\K\h+
• Replace with: \n OR \r\n depending on platform
• CHECK Wrap around
• CHECK Regular expression
• Replace all

Explanation:

^                   # beginning of line
    (?:             # non capture group
        \S+           # 1 or more non space
        \h+           # 1 or more horizontal space
    ){4}            # end group, must appear 4 times
    \S+             # 1 or more non space
    \K              # forget all we have seeen until this position
    \h+             # 1 or more horizontal space

Screenshot (before):

Screenshot (after):