First, figure out the intent and what's the delay. Depending on your product and how new of a category it is, people don't just care about features. They are looking for eBooks, references, case studies, showing the benefits and key results, then you can talk about what are the next steps for them to get there. Ideally, this should be data driven and targeted. Do not suggest a trial extension automatically.
You can also try to have different drip campaigns depending on their:
Role and seniority in an organization
What they did (it will depend on the customer using a specific feature of your product)