My favorite crankbait is a rattlin rapala, and the description says it can be fished at any depth. I have caught many fish on it in a lake that was 1-2 feet deeper due to rain, but haven't had much luck since.How do I control this depth? (I use fluorocarbon line) Thanks!

thicker line will cause it to run shallower,thus thinner line will run deeper. retrieve speed,rod angle,length of cast all pays into lure depth. a rattlin rapala will sink if not reeled in right away so letting it settle after the cast you can also adjust depth. play around with all of this to see what works for you. good luck.

After reading crypt's reply, I don't think there is much to add at all!  I'm not sure if Rattlin' Rapala's come in different weights.  If so, that will also have an affect.

If you fish spinnerbaits, then control the depth the same way. Cast it out, close your bail and let it sink to the desired depth before starting your retrieve. Reel too fast and it will rise, or too slow and it will run deeper. 

Another way to control the depth of a crankbait is with the rod. Hold it high to go shallower or low to run deeper. Paul Elias used the "kneel and reel" technique to win a Classic. He actually stuck his rod tip in the water to get extra depth,

A little spit shot a foot in front of it to make it run deeper.

The lure the OP mentioned is a lipless crank and although rod position plays a minor role in how deep it runs, letting it sink to a desired depth is the key

Let it sink , thats what makes it versatile . I like to hop lipless lures off the bottom in deep water .