2 ways,

1. get some cardboard and sand the surface of the blue tape (or very very fine grit wet and dry sand paper) but something soft, just rub it all over the blue tape to make the surface more matte and not so porous. It turns a little whiter blue when this is done.

2. Cook the tape for an hour. Put your hotbed on 110c and dont print anything... then run another preheat, this expands the tape and also fills in the minute surface on the tape, which to the human eye looks smooth but even under a USB microscope is like a tonne of fiber layers bound together, and It I think it's that porous structure that makes it stick so damn well, sort of like how hip joins and such are made with porous sections to allow the bone to attach and graft, or like joining two pieces of clay together with a criss cross in the join.