Too many businesses give up so it's great to hear that you are up and going again.
I recommend spending a lot of time on comms. Reach out to existing/current customers and stakeholders and be as transparent (about the past & future plans) as you can to help build trust and hopefully mend relationships.
The best example of that in the marketplace to date is Buffer. They are a little crazy as they are a fully open startup but I admire what they are doing and even taking 10% of their approach can prove wonders for any venture (new or old).
Next, I would focus on surveying those customers to really show that you listening and want to build something even better than before.
Following on from that work with your team to incorporate customer feedback. Then look at your persona's and marketing channels for early exposure.
Be careful not to go overboard here - Good marketing and exposure can be achieved without having high acquisition costs. Testing is your friend and allows you to double down on what works and to drop what doesn't.
If you have any questions please don't hesitate to reach out.