Adjusting a declined offer's hide time
By default - a customer that declines an upsell offer will not be shown this offer again for 14 days.
From the Settings page - locate the Upsell Popup Settings section.
You can adjust how many days the declined offer should be hidden for.
"but wait.. I don't want to hide the declined offer at all"
If you'd like the declined offer not to be hidden - please set the days to 0. Please note that they will get the popup after every refresh though so this is not advisable.