The only way to reset your Replika is to delete your current account and create a new one. Please, keep in mind that the items you've purchased via Store can not be moved to a new account. Your Replika profile, badges, levels, XP, chat history, photos, and links you exchanged with your Replika will also be permanently removed. The subscription status, however, will remain unless you purchased it via Stripe. Subscription plans purchased via Stripe can not be restored.
Read more here on how to delete your account.