Possibly, if the current assignment still supports L-1B eligibility and the appropriate immigration steps are satisfied. The answer depends on whether only timing changed or the actual work, supervision, worksite or employer also changed.
Review the current assignment
Document the remaining specialised duties and the business plan for the delay. Do not assume the employee may enter to perform any available task because an earlier project was approved. If the proposed role no longer involves the claimed knowledge, a revised business plan alone may not preserve the original case.
A delay is not in itself an obstacle, but it does mean the case has to be assessed against the assignment as it now stands rather than the one originally described. Establish what the employee would actually do during the period in question. Where the original project is deferred and interim work has been substituted, that interim work is what needs examining: does it require the specialized knowledge the case rests on, or is it general work that any competent professional could perform?
Where the answer is the latter, the difficulty is substantive. Where the original project remains intended and the delay is short, the position may be unchanged. Establish the facts and put them to counsel rather than proceeding on the basis that an approval, once given, covers whatever the assignment becomes.