It depends on your previous sin. Is it still valid? If not (It is not hard to imagine, given that you applied for BOWP) I would say renew it. Because for PR, you need to wait for the final review and pr, then you need to submit your passport, receive the COPR and do the landing. After landing, you are eligible to get a new sin number. All these might take one month and if you are working, you need to have a sin to receive valid payments. Plus, renewing sin is free and it won't hurt if you renew it.
PS: with BOWP, your sin won't change, they just update the expiry date. But, with COPR they will change your sin and will give you a new number.