Regex to replace values that include part of match in replacement in sublime?

The replacement expression is:

\$\1\u\2

• \1, \2 are the captures (or $1, $2)
• \u up-cases (see the Replacement String Syntax section).

See the Regular Expressions chapter ^{(in the TextMate docs)} for more information.

There’s already a package that does this, and more:

• Brief blog about CaseConversion
• CaseConversion package