续 (xù, 'continue') +
保 (bǎo, short for
保险 bǎoxiǎn, 'insurance') = 'continue the insurance'. The
续- prefix is productive for renewal/extension terms:
续约 (xùyuē, renew a contract),
续签 (xùqiān, renew/extend a signed agreement),
续费 (xùfèi, renew a paid subscription).