How can we upload a jpeg file that is larger than allocated?

Change the upload file size in your form, this guide will help you to do it: http://www.jotform.com/help/33-Changing-the-Upload-Size-Limit. 

Do note that this uses your upload space in your account, as you are using a free account you only have 100 MB, once you reach the limit you will receive a message and then you will need to delete your submissions in order to get free space or you may upgrade your account to get more space without the need to delete your submissions: https://www.jotform.com/pricing.