Hi Boon,
You can recertify your JNCIS-ER by taking either the JNCIS-ENT or the JNCIP-ENT.
If you are currently a JNCIE-M, then yes passing the JNCIP-SP will automatically recertify your Expert level, and also transfer your JNCIE-M over to JNCIE-SP.
Regards,
Kieran Milne
Tech Lead, JNCP