Iqama must be renewed before its get expired. Keep in mind or calender yourself for an alarm 3 days prior before your Iqama gets expired.
Its the responsibility of the the employer to renew your Iqama and pay the fees. For expatriates working in government organizations the organisation will take care fo new Iqama and Iqama renewals.
Relaed Article: Iqama Renewal Steps
Penalty on Iqama Expiry
Penalty for failing to renew the Iqama for the first time is 500 SAR and second time is 1000 SAR
Lost your Iqama in KSA, Here is a great article which explains what to do if you lost your Iqama