Shit on her. (i've always wanted to use this) But seriously, just go up to her, ask her for a serious talk and tell her the benefits of trials, and try to be grown up about it, and if at any point she doesn't agree either go back to what i first said, by shitting on her, or tell her shes being childish. Try to get her in a position where she can 'be in your shoes', then she'll hopefully recognise how fun it is. If you don't succeed, trials is shit anyway, you woudn't like it. If only mate, if only.