The following is based on additional clarification from the question submitter:

The situation you describe calls for a Requirements or Time and Materials contract type for the repair line items rather than an Options clause. Of course if the contract may need to be extended beyond a base year, then an Option clause is called for. The Options clause is used to add one or more additional years to the base year rather than for the specific purpose of funding separate CLINs. As for incremental funding, DFARS 252.232-7007 is appropriate if the repair items are fixed-price.  The Availability of Funds clause is appropriate if the contract is initiated before funds become available, so it would apply for the repair and replace CLINs only. The Limitation of Funds clause is applicable for cost reimbursement type contracts, which isn't the case if you will be using a time-and-materials contract type.