A tried-and-true technique to build energy into another part of a song is to use a drum fill — it works every time! But if you’re looking for an alternative, why not try a synth “riser”? Popular in dance music, this is the technique of using a synthesizer sound and raising the pitch gradually. This isn’t done by playing successively higher notes, but by using an envelope with a long attack to control oscillator pitch/detune, or by opening a high-pass filter cutoff.
The process of creating a riser is simple: play a steady note or repeated part, then set a synth envelope to modulate one or more parameters that give the effect of a steady, constant rise in pitch or an opening high-pass filter. When done correctly, this can create a sense of energy and urgency that might be exactly what your song needs to propel it to an even higher level — give it a try!