DEET will soften the varnish making it tacky again. If it wont dry back down you will have to sand it down and re stain/varnish it. One other option (a risky one) would be to try denatured alcohol to remove the tacky varnish and then just revarnish it with a wipe on varnish. I guess if it isn't usable the way it is then you have nothing to lose. Good luck!