import re
def abbreviationsDict():
    return {'ref.': 'reference', 'ref:': 'reference', 'approx.': 'approximately', 'no.': '', 'nos.': ''}
pattern = re.compile(r'\b({})(?!\w)'.format('|'.join(re.escape(key) for key in abbreviationsDict().keys())), flags=re.I)
s = "Variation of Condition on planning application Ref: CB/15/03633/FULL dated 30/11/2015: Condition 9"
s = pattern.sub(lambda x: abbreviationsDict()[x.group(1).lower()], s)
print(s)