Hi,
You can edit the prefix-list and do a load merge.
Before that you may need to use some scripting or editors to append the ';' to the prefix list.
I normally use sed on *NIX to append the ';'
Example:
> sed -e 's/$/;/' prefix.txt
Then, edit policy prefix-list xxx, load merge relative terminal. Example below:
[edit policy-options prefix-list TEST] root@PE2# load merge relative terminal [Type ^D at a new line to end input] 94.38.108.24; 94.54.42.82; 94.61.171.253; 94.62.98.162; 95.128.34.171; 95.139.161.113; 95.141.27.91; 95.141.31.16; 95.141.31.19; load complete [edit policy-options prefix-list TEST] root@PE2# show 94.38.108.24/32; 94.54.42.82/32; 94.61.171.253/32; 94.62.98.162/32; 95.128.34.171/32; 95.139.161.113/32; 95.141.27.91/32; 95.141.31.16/32; 95.141.31.19/32;
There might be other ways of doing this, network automation using Ansible or Junos space for instance, but those do not involve the JUNOS CLI.