Hi,
if your baby des not like cold apple juice, it should be heated.
If your baby does not like cold apple juice, it should be heated.
Grammatically, 'it' refers to 'apple juice'. However, if you are worried that it might seem to refer to 'baby'
, then you can reword the sentence as
You should reheat cold apple juice if your baby does not like it.
Best wishes, Clive