Kestrel nest box

I had a kestrel nest box put up on a dead willow tree in 2021 and after I had a tree surgeon put 2 - 3 inches of wood shavings in it a pair of kestrels nested in it and raised 4 chicks.  The pair have been on the tree with the nest box numerous times this year, but recently have started looking at the dovecot where they nested in 2020.  This is way too small and I can't bring myself to see week old chicks falling out of the dovecot again.  I phoned RSPB in Sandy and they told me needs new bedding each year.  Do any members of this forum have kestrel nest boxes they manage and if so do they advise getting the bedding renewed?