Install a devmode edge channel snap from the store (such as peek). The developer is actively working on the snap and as such is revving the snap frequently. Typically we talk to developers and users about snaps being kept up to date automatically in the background. So they know they'll get the latest version of the edge devmode snap when the developer pushes.
However, that doesn't work for devmode snaps:-
Here is one I installed some time ago:-
Name Version Rev Developer Notes
peek 1.0.1+git 60 phw devmode
I am tracking edge:-
alan@gort:~$ snap info peek
summary: "Simple animated GIF screen recorder with an easy to use interface"
Peek creates animated GIF screencasts using FFmpeg and ImageMagick. It was
built for the specific use case of recording screen areas, e.g., for easily
showing UI features of your own apps or for showing a bug in bug reports. It
is not a general purpose screencast app with extended features and it never
installed: 1.0.1+git (60) 71MB devmode
refreshed: 2017-04-06 10:40:38 +0100 BST
latest/edge: 1.0.3+git (165) 71MB devmode
Force a refresh of all snaps:-
alan@gort:~$ snap refresh
All snaps up to date.
Force refresh of that one snap:-
alan@gort:~$ snap refresh peek
error: snap "peek" requires devmode or confinement override
alan@gort:~$ snap refresh peek --devmode
2017-06-16T08:47:06+01:00 INFO cannot auto connect peek:x11 to core:x11: (plug auto-connection), existing connection state "peek:x11 core:x11" in the way
peek (edge) 1.0.3+git from 'phw' refreshed