s/
    (?<=                  # Look back-group
     weak                # Match the word weak
     <INPUT TYPE=radio NAME=     # tag
     (                   # Capuring group: $1 / \1
       \w{2}\d\w{2}      # 
     )                   # End-capture
     VALUE=\d>           # tag
 
     (?:                 # Non capturing group
       <INPUT TYPE=radio NAME=     # tag
       \1                # It's possible that this should be $1, as I said, the code is untested.
       VALUE=\d>
     ){6}                # There are 7 input tags, one already matches, so 6 to go.
     )                   # End look-back
     (?=                 # Look-ahead-group
       strong
     )                   # End look-ahead
   /
     the text you want to insert
   /ixg;