Finding new words from characters I already know

I'm a beginner at Chinese - only know about 400 characters. I know 请 and I know 假 from 寒假 and today I found out that 请假 means to ask for leave when I read a class roll. It got me thinking about how many other new words/terms I could learn from the characters I already know. If there a tool out there where I can import a Pleco or Skritter list of all the characters I know and find out what new (to me) terms I could learn that use the characters I already know?