I am also a member of a chapter of the Elizabeth Ministry at our parish. We have also had the problem of finding volunteers. When I joined 6 years ago, we had a nice group of about 25 women. Now, it is down to about 6 core people, and only about 3 new ones joined after me and are not that active.
We also have trouble reaching the expectant moms. Each month we have a special blessing at the 11:00 Mass for them. Months can go by and no one comes forward for the blessing. (we give them roses) That was a good way to meet the young parishoners, but not so good anymore.
One really good thing we came up with was the Mother/Daughter Tea. It is a major event in our parish now. On a Sunday, we sell tickets to the tea ($10.00 for adults, $5.00 for kids) and make a light lunch for them. We have donated baskets of stuff to raffle off, and some entertainment like Irish Dancers or storytellers. We average 300 people in attendance, often having several generations come out for this.
It is a lot of work for us, and many husbands help out in the kitchen, but it pays off when you see how much fun people have. And now we actually have some money to carry out our mission of helping those in need during childbearing years.