You can also insert bars. Edit > Insert Bars... This may work better than nudge for your purpose if you want to keep the remaining chords on the same downbeats they were originally.

If you want to insert one and a half a measures you could start by insterting 2 bars, then decrease the number of beats in a measure to get that 1/2 bar by pressing F5 and changing "# of beats this bar". Then in the measure you want to go back to 4/4 press F5 again and change "# of beats" to 4 again.

Note, If you use nudge instead of insert bars you will probable have to manually edit the "bar for end of chorus" box to make the song longer.