Certain versions older versions of the Google Keyboard had a bug that impacts backspace operation within JuiceSSH.
The symptoms are that you can only press backspace once per character typed into the terminal.
For example, if you login to a server and press up to view the last command, you then would not be able to use backspace to remove that command.
Prior to version JuiceSSH v1.4.12 (released May 2014), JuiceSSH included a workaround for this Google Keyboard bug however the workaround could cause lag on the terminal in certain circumstances.
Google have now fixed the original bug so we removed our workaround in JuiceSSH v1.4.12.
If you are still experiencing problems related to this, please visit this Play Store link and make sure your Google Keyboard is updated to the latest available version:
https://play.google.com/store/apps/details?id=com.google.android.inputmethod.latin