How to pull Sqlite database from a Django app running on Heroku?

So I am working with a simple Django app which uses Sqlite for persistence. I have been able to push all my changes onto Heroku and everything works online. The problem is that I want to once in a while synchronize changes made in the live environment (on Heroku) onto my local machine. A command such as

git pull heroku master

returns

* branch master -> FETCH_HEAD Already up-to-date.

So I am thinking that I need to manually pull only the changes in the live database. I have tried doing something like heroku db:pull and heroku pg:pull but without success. What am I missing?