Is there a way to get Odoo to update the stock 'cost price' from BOM to include labour costs? I am running Community Ver15
There are two options to achieve your requirements.
1) You can add the labour cost or other expenses in work center per hour cost.
2) You can add the new section for labour cost and other expenses. In that you can create entries of labour cost and other expenses for particular manufacturing order. For this point you have to extend the functionality in existing odoo flow.