Related Clues:

• Gets through twice, as a book
• Sharpens, as skills
• Peruses again
• Studies carefully, in a way
• Sharpens, as a knife
• Makes keener
• Makes sharp
• Works on
• Zeros (in on)
• Makes sharper
• Sharpens the edge of
• Cutting-edge creators
• Double-checks
• Tweaks
• Enjoys the book anew