To re–engage users with an app, use the following strategies:

Build remarketing lists, engage in reactive outreach, offer something free, and don’t track anything outside of installs
Build remarketing lists, engage in proactive outreach, offer something unique, use deep linking, and track everything beyond installs to understand your most valuable users
Build remarketing lists, engage in reactive outreach, use deep linking, and track outside of installs for your most valuable users
Build general email lists, engage in reactive outreach, don’t use deep linking, and don’t track outside of installs