Update: noweb references
I misunderstood your question. My original solution works for text outside of code blocks, when you asked for updating values inside code blocks. To accomplish this, we can use (org) Noweb Reference Syntax. This allows us to insert the value of one code block in another. Using your example, this looks like:
#+TITLE: My Nice Class
The python implementation in Org babel has a couple of long-standing problems:
If you specify :results value, then the body is implicitly wrapped in a function and you have to add a return statement to indicate the value of the block - but only if you are not using a session.
If you specify :`:results value but you use a session, you have to wrap the body ...
(org-collect-keywords '("PROPERTY")) could also be helpful, as mentioned in https://emacs.stackexchange.com/a/63102/31740.
The org-collect-keywords doc string states:
Return values for KEYWORDS in current buffer, as an alist.
KEYWORDS is a list of strings. Return value is a list of
elements with the pattern:
(NAME . LIST-OF-VALUES)
where NAME is ...