Yeah, you will need to reapply for the mortgage , same happened to us with a delay in the sale a while back. But given that AIB will have your info from your current offer it should only be a matter of updating your financial info and, if nothing has changed adversely on that front, you should get your approval updated fairly quickly. You should really discuss this with your solicitor - can he/she insert a clause in the contract that it's subject to mortgage approval ? Also, you will need to get your mortgage protection cover sorted if not done already.