Your prospective parents are in your community and they aren’t coming into your school why not go out to them? There are lots of venues within all communities that have a large amount of footfall and passing trade to enable you to target a large amount of people at minimal cost.
Take your local supermarket for example, all parents will visit their supermarket. Approach your local supermarket and ask if you can put a stand (pull up banner), take leaflets, giveaways or something to attract people over. Get some of your current parents to represent the school and approach people who have young children with them, ask if they have their child enrolled at the school. If they don’t invite them to a parent/child play session at your nursery and collate their details.
There must be several mother and toddler groups operating in your area, find out who hosts these and approach them and ask if you can go along and give some information on their school or work with them to host a messy play or education session with their toddlers.