Hyper-v 2008 r2 Cluster migration to Hyper-v Cluster 2012 r2

i have case to do:_

i have 2008 r2 Hyper-v Cluster (3 NODE)

inside this cluster we have another SQL Cluster  and Application Server

and some attached  LUN direct to VM'

plan:_

to move all above to existing 2012 r2 cluster (5 NODE)

Note :- I know that we cant Export from 2008/2008 r2 to Import 2012 r2 

any Idea how we done this issue