You do not need to update BIOS when upgrading from Windows 7 to Windows 8. To know more, refer to the following Acer Support page:
To check if there are any BIOS updates available for your Acer E1-571 and to update the same (if you do not have the latest ones installed already), you can follow the steps mentioned below:
Updating BIOS incorrectly can harm the performance of your device. Be very careful while selecting and downloading an update. Make sure that it is compatible with your Windows version. You can do this by going through the instructions on the following web page thoroughly.)
1)Go to http://us.acer.com/ac/en/US/content/drivers
2)Type "Aspire E1-571" (without quotes) in the box under "Search by Product Model" title
3)Click on "Aspire E1-571" that appears in the search list below the box. If the search results do not appear, simply click on "Search" tab besides the box.
4)Your product "Aspire E1-571" will get displayed.
5)Click on "BIOS" menu in the table that appears
6)Go through all the BIOS files carefully. If there is any BIOS update available for your device, click on "Download" option of the respective file.
7)Once the file gets downloaded in your system, run it and follow on-screen instructions to install BIOS updates.
Hope this will resolve your issue.