Unfortunately that can be the case with some insurance plans, especially privately paid insurance plans. It would be nice if all insurance plans were equal for this and realize that when you are discussing hospice, the last thing you want to deal with is money and it most cases can deal with.
Look at your hospice closely, if they are not for profit (the Home Health and Hospice I work for is) then they will often write off the financial piece of it. Also look and see if you have a second hospice available in your area. Quite often areas have one that is larger and more well known while there is a second smaller agency. The second agency may be non-profit or be willing to work with you on the finances.
Lastly appeal to your insurance company. They have the ultimate decision and I know that some will drop the co-pays and deductibles, especially in a situation like this.
I have a firm belief that NO ONE should have to pay anything for hospice care. You are already dealing with the most stressful time in your life and there is no need to have to worry about finances.
We had a similar story at work just recently only this young woman's plan only allowed her to have 15 days of hospice care in her lifetime. She was very ill but we knew she would be here longer than 15 days. We took her on and will write off anything her insurance does not pay.
Hope you can work things out.
Any advice given is based on my experiences and should not be substituted for any medical recommendations. Please speak with your provider before making any changes.