I have what looks like a big square eraser on a stick, that's meant for cleaning sandpaper it works really well for extending the life of your sandpaper when it gets clogged with epoxy
Why is epoxy clogging your sandpaper?
Usual result is it comes off as dust, not sticky... unless you try to sand too soon, in which case that residue may be somewhat toxic owing to the incomplete reaction between resin & hardener.
Best not to inhale that stuff or the sanding dust either, it doesn't play well with our human bodies' tissues.