Every person who buys your front-end product should be given as a bonus:

"Free eBook/CD/Video Just For TRYING (Frontend)"

Basically a one month free subscription into your continuity program. It shouldn't be forced, but it should be "checked" at your order form.

Your affiliates will appreciate the monthly commission, and your conversion on the continuity will be very high.

I learned this from Eben Pagan, who stated in his Altitude program that 1/3 (!) of his $20m business is based on his $19.95/month continuity programs!