If you have funnels for the checkout process I would analyse if the conversion rate has dropped historically and if so, if it then relates to a drop of visitor traffic.
Just because a user adds an item to the cart is not necessarily a very strong purchase intent. Depending on the vertical conversions might just be okay if in the range of 3-5%. Reading through whitepapers, cart-abandonment seems to average at around 60%.
The funnel analysis would be your first starting point (in conjunction with a visitor analysis - i.e. newly registered users vs repeat buyers).
I would improve conversion through some call to action:
- Display a "only xx left" or "save XX %".
- It sounds your cart is saved - in which case you can send follow-up emails with a strong call to action - similar as above or offer a coupon/discount if checkout is done with 24 hours