Pad the anacrusis?? Why (unless there are special rhythmic reasons). The last bar of the piece should be adjusted. eg if 4/4 has a crotchet anacrusis the last bar should have only three crotchets- so possibly a dotted minim rather than a semibreve: otherwise the rhythm will jump when you repeat.
nwc annoyimgly insists on padding the last bar with rests!