I have configured PCC to load balance two wan connections and its working fine.

When WAN-1 failed, all load goes to WAN-2,
but when WAN-1 comes back, WAN-2 load doesn't shift back to WAN-1.
Only new connections get load balanced across both WAN's.

Is there any way that after wan1 recovery, existing load on second wan shifts back to wan1.

It is required because most of my users schedule downloading of very large iso images for night from the internet. When they start downloading big files, and WAN1 goes down, all load goes to WAN2, but when WAN1 comes online, previous load doesn't shift back and wan1 sits idle all night.

PCC is connection aware so new connections would remain on the existing path. The only way to change that would be to reestablish the tcp connection.