When packages run, they cannot update themselves, so a wholly package-based solution is not the way ahead.
However, your package can read from and write to a metadata table inside a database. Perhaps this gets you what you want?
Even better (as it's self-contained and infinitely re-runnable) would be to derive your variables from run date. If you are able to do this and can provide the logic, we can help you implement it.
If the answer to your question can be found with a brief Google search, please perform the search yourself, rather than expecting one of the SSC members to do it for you.