import re
p = re.compile(r'var\d+(?:(?!var\d).)*?secondVar', re.DOTALL)
test_str = "var12.1\na\na\ndsa\n\n88\n123!!!\nsecondVar12.1\nvar12.1\na\na\ndsa\n\n88\n123!!!\nsecondVar12.1"
print(p.findall(test_str))