import re
def replacer_factory(spelling_dict):
    def replacer(match):
        return '{0}{1}{0}'.format(match.group(1), spelling_dict.get(match.group(2), match.group(2)))
    return replacer
 
repkeys = {'modify': 'modifyNew', 'extract': 'extractNew'}
pattern = r'''(['"])(\w+)\1'''
replacer = replacer_factory(repkeys)
filedata = """<fn:modify ele="modify">
<fn:extract name='extract' value="Title"/>
</fn:modify>"""
print( re.sub(pattern, replacer, filedata) )

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