Change your policy while grandfathering your existing “full access” members. You could make this into a “Last Chance” promotion to get full access for life. That way anyone that was on the fence will likely jump to get full access,
Then you could offer lifetime access to individual courses, including a low introductory price on the 1st course. You could also include a mid-priced offer for lifetime access to any 3 courses they choose, and finally, premium-priced lifetime access for all products. This gives you a sales funnel OTO opportunity that will likely double or triple your average order value while significantly boosting lifetime customer value at the same time.
You could create one or more new websites and launch new products under different domains. You could easily create one new website for each new product and use these products as lead magnets for your lifetime membership website.
In fact, I see no reason you couldn’t implement both ideas.