Semi permanent hair dyes

Hi
I want to dye my hair a pink colour for the summer, but my parents aren't allowing me to bleach my hair in case it's not out by the time school comes back around. (However my hair is already a dark blonde colour) So after doing some research I had decide on the brand manic panic in the colour hot hot pink, as the site said it was good for unbleached hair & from what I can see it shows up quite vivid and I like the shade. Despite all this I've taken another look and seen that it only lasts 6-8 washes, and from reading blog and knowing how often I tend to wash my hair this's only be a couple of weeks or so. So since I don't want to pay out to dye my hair a second or even third time over the 6/7 week holidays (not to mention howtime consuming this would be) I was wondering if there were other semi permanent dyes out there which would last any longer, are a similarish colour and would do ok on non-bleached hair. Thanks!
(P.S Also if it helps I do have virgin hair!)

Semi-perm dyes can never last overly long as their not staining your hair. What I will say is that mixing a few drops in with your conditioner when you wash your hair it can make it last a bit longer,its what i used to do with mine and it lasted 3/4 weeks instead of just two. From what I know manic panic is the longest lasting one of them all apparently.