What version of Premiere Elements are you using and on what computer operating system is it running?
Besides the narrations on the Timeline, do you have audio on the numbered audio tracks and on the soundtrack? If so, are they lost in the export as well as the narration?
What microphone are you using with the Premiere Elements Narration Tool? And if you have not already, please create Premiere Elements narration with its narration tool with the Audio Meter visible (Window Menu/Audio Meters) to verify that the sound is at 0 dB or thereabouts in the Audio Meter channels.
What are the details of the export?
If you create your narration with the free audio editor Audacity and use that as the narration in your Premiere Elements project, is the narration sound lost in the export?
Let us start here, remembering that the answers are in the details.