Thanks for posting !!
If you run $ ask deploy then it will deploy whole skill and lambda code but if you want specific part to deploy like you have change only lambda code then you can run :
$ ask deploy --target <target> --debug
Accepted values for `target` are: `all`, `lambda`, `skill`, and `model`. The default target is `all`, if not specified.
Check this link for more details.
ASK deploy with account linking 3 Answers