It is possible to restart after the last finished macro iteration in (MC)SCF, provided the "f21" file was saved. You will then at most loose part of one macro iteration in case of system crashes, disks running full, or other irregularities.
In general the only change needed to the wave function input is to add the .RESTART keyword under **WAVE FUNCTION . If the correct two-electron integrals over molecular orbitals are available, you can skip the integral transformation in the beginning of the macro iteration by means of the .OLD TRANSFORMATION keyword under *TRANSFORMATION . When resubmitting the job, you must make sure that the correct "f21" file is made available to the job.
You can also use the restart feature if you find it desirable to converge the wave function sharper than specified in the original input. By default, SCF wave functions are converged to 1.0D-6, whereas MCSCF and CI wave functions are converged to 1.0D-5.