Lager Yeast reuse question

So about a month ago I brewed 5 gallons of a low gravity light lager and was thinking of reusing this yeast for another batch of the same thing. what steps should I take to make the starter for this? I have a stir plate and all the fix’ins to make a starter but could anyone share some insight on how to bring the yeast back to a fully healthy and happy culture? Thanks in advance.

I tell what you I did recently and it worked, but may not be the “by the book” method. I took 1/3 cup of the saved slurry and did a 2l starter. when it finished, I cold crashed, decanted and used that for a 1 gal starter. This was for a 5 gal lager of 1.048 OG.