There are loads of ways to generate new ideas. Below you will find a few that will help increase your idea generating capacity which is a function of intelligence increase. This increase may not be in the real/raw sense, but in the sense that you will be more educated and able to express ideas more than anything else.

1. Use the techniques in The Complete Guide To Genius.

This will bring a ridiculous amount of ideas to the fore. There is no excuse for laziness. If you wish to increase your intelligence or idea generation capacity and do so consistently, this is clearly an investment you need to make in yourself. 

2. Get other people's opinions.

Sounds like a no brainer but seem people seem to shy away from getting the perspective of another person. The trick here is to trade. Ask for an opinion after offering the person value. The person's opinion may allow you to see things from a distinct and unique point of view. It may give you ideas that you would not have thought about.

3. Educate yourself.

If you want to generate new ideas about a topic, it is a good idea to learn as much as possible about that topic. Sources for this can be the internet, books etc. As you understand other people's ideas, you will be in a better position to being your own ideas to the fore. Thinker A says XYZ and thinker B says ERT. Therefore I say LRU.

4. Experience your ideas first hand.

Go to a physical place where you are likely to gain new ideas. This may be a thought group who have formed to discuss similar topics, or you could go to a historical or famous site which is linked to your topic.

5. Brain Storm.

One of the easiest ways to generate ideas. Set yourself a time limit to get the required information from your subconscious. You will be surprised at how much you can do in such little time. The value of a time limit means that there is no time to mess around, and this pressure brings mental efficiency out of you to get the work done.  

6. Mentally focus on your topic.

The more you focus on it, the more the energy that goes into it. This will bring new ideas to you and allow you to contribute and expand in the topic.