Yes.
Sublime text supports regular expression and you can select all non-ASCII (code point > 128) characters. This regex find should be enough for you:
[^\x00-\x7F]
Just search and replace.
But if you are doing manual HTML encode in the first place you are doing it wrong. Save your files as UTF-8 encoding (Sublime Text 2 default) and make sure your web server also sends out those files as UTF-8. No conversion, encoding or anything needed.