import re
regex = r"(c(?:\+{2}|#)|\.net\b)|[!,.:;/—]|-(?=[\d.])"
text = 'Must-have skills: -.Net programming experience; -2 years experience in C++; C#/.Net, C++/.Net, C./.Net.'
text = re.sub(regex, r"\1 ", text, 0, re.IGNORECASE)

if text:
    print (text)