I toiveled an (plastic) item and then realized there is a rubber band around the exterior which is removable. Do I need toivel it again without the band on?

 

No.

You would only need to toivel it again (without a Bracha, of course, being that it is plastic) if the rubber band is not used as part of the utensil.

 

דרכ״ת קכ, צו. הר צבי יו״ד קח. שו״ת מנח״י ג, עז. טבילת כלים ב, ז.

 

#9943