You've done great so far because most of your list as you said are already customers. It's easier to get someone to buy from you again, than to get them to make the initial buy.
So now you have a number of options. One thing i'm not clear on though is that you said you have another ebook and a "higher-ticket" item, but then you said you have a lack of products.
3 products in the funnel is just fine and dandy. So you could do a couple of things.
Make the new ebook an upsell <---pre-purchase
Make the new ebook a OTO <---post-purchase
to the folks who bought the first ebook, you should have an autoresponder series in place selling the 2nd ebook for you.
For the higher ticket item, do a little mini-launch to your list. Warm them up, get them drooling, and spring it on them.
Then after that, just sell it in your Autoresponder series.
Also, if you are not doing this already, you should definitely have your prospects on a separate list from your customers.
You should also have repeat customers on a separate list as well. If you have Aweber they make it super-easy for you to do.
The idea is to have the whole process in place so you really don't have to do that much. That's why autorresponders are so great - they allow you to do this.
Hope that helps.
Jay