There are 2 ways to make it, win10, conda python3.6.7, Ipython7.1.1, Sublime 3.1.1
1.Open \Packages\SublimeREPL\config\Python\Main.sublime-menu, find the line
"windows": ["python", "-u", "${packages}/SublimeREPL/config/Python/ipy_repl.py"]
and change it to where your ipython.exe located, for me is
"windows": ["C:\\Python\\envs\\py37\\Scripts\\ipython.exe"]
2.Just modified \Packages\SublimeREPL\config\Python\ipy_repl.py to 3 lines,
import os
# change dir to path_to_ipython.exe
os.chdir(r'C:\Python\envs\py37\Scripts')
os.system('ipython')
I prefer the second one, if you encount problems with first way, such as your shortcut about sublimeREPL not work (happens to me:(), try second one.