Harvest slurry from your fermenter and pitch that. Do not put fresh wort onto an entire yeast cake. It is not good brewing practice.
Harvesting is insanely easy: Clean and sanitize a scoop. I used a stainless-steel kitchen measuring cup; glass works also. Clean and sanitize several Mason or glass jam/peanut butter jars. Carefully - you don't want to nick or scratch the plastic fermenter - scoop up enough yeast to fill each jar halfway. Seal tightly and immediately refrigerate. Use within seven days. Now go clean that filthy fermenter.
For most beers (OG 1.040-1.060), a cup - 8 fluid ounces - of slurry is an appropriate amount of slurry to pitch. The formulae and in-depth information is yours if you want it; PM or email.
One of these days, I'm gonna just write this into a file and save it, so I don't have to rewrite it over and over again.