I've never used premixed insulin and it's a long time since I've injected twice a day!
But if this is the regime that you are currantly on then you need to contact your DSN ASAP so that you can discuss what regime to move to, either another pre-mixed insulin by another manufacturere (very few about if I remember rightly) or perhaps changing over to the basal/bolus regimes..
If you wanted to stay with the same insulin then there is a way around it, as it a premixed of both an intermidate insulin and a quick acting insulin both are avaiable separtely in vials, you would have to draw up from each vial of insulin into one syringe to inject!
But speak to your team, as they aren't always aware who is on what regime/insulin until they've got your medical file in front of them