Pip review, asking for ongoing/ 10 year award

I'm just in the process of filling my review form in.
Been I receipt of DLA/PIP for 12 years, in which time my points have always gone up, however my awards have from 4 to 3 to 2 years despite my many illnesses and degenerative conditions and also solid supporting evidence.
I strongly believe I should be awarded an ongoing or 10 year award( I'm 59 now).
But is it being a bit cheeky asking for this on the pip review form?
What would be the best way to word it?

Thanks

Thanks, really appreciate your helpful reply

I wrote on my son's renewal that autism was a lifelong disability and as he hadn't made any developmental gains in the last fifteen years it was unlikely that, going forward, he would be making signicant gains in the next fifteen. He got an ongoing award on a paper review so I'd say it is worth a go.