Here are some useful tips to solve this issue
Bundle two or more products and make an offer. Customers like to buy a product which is more than one. Some innovation is required to make the offer juicy.
Discount Vouchers and Coupons
Use the product promotion feature to provide customers with coupons both on products and on their purchases. Send out these coupons to the long list of existing customer base that you already have. Customers would also feel delighted that they are remembered and rewarded for shopping on your store.
You can also list your products on market places eBay, Amazon etc where you can get the sale quickly. Only issue will be the cut throat margins that you have to manage with these market places.
Remember, instead of spending huge on operations and warehouse, its better to get rid of the dead stock and still make profits. E-commerce stores are a nice way to get these done. Innovation is the key here.