Gives a new value to

• Downgrades, e.g.
• Bumps an R down to a PG-13, perhaps
• Changes at Standard & Poor's, say
• Changes a grade
• Changes a review
• Considers bond values again
• Alters an assessment
• Gives another star to, perhaps
• Changes at Standard & Poor's, say

Wiktionary Word definitions in Wiktionary
vb. (en-third-person singular of: rerate )