Renewing your Oauth token on every API request is time-expensive and too many frequent token requests could result in your application's token becoming revoked. Reference
Instead of trying to avoid sending a request with an invalid token, you should consider implementing a callback or interceptor which would check if the response contains an error code and then appropriately handle the error (display an error message or automatically redirect to request for authentication). The callback/interceptor pattern allows this error checking to be triggered automatically when each request has completed.