CFI endorsement ?

[Stets656]

Student pilot walked in and had previously solo'd. His 90 day endorsement expired and needs a new one. Do I need to administer new knowledge test and all new endorsements or can I just add on an additional 90 day once I find him proficient in the airplane?

 

[PeterNSteinmetz]

61.87(b) Aeronautical knowledge. A student pilot must demonstrate satisfactory aeronautical knowledge on a knowledge test that meets the requirements of this paragraph:

Does this apply to the repeat endorsements after the student has their initial solo endorsement?