The SCAMPER technique (created by Michael Mikalko), will assist you in thinking of changes you can make to an existing product to create a new one via a checklist, these can either be used directly or as starting points for lateral thinking.

SCAMPER is an acronym which stands for questions relating to the following:

S - Substitute - components, materials, people
Think about substituting part of your product/process for something else. By looking for something to substitute you can often come up with new ideas

C - Combine - mix, combine with other assemblies or services, integrate
Think about combining two or more parts of your probortunity to achieve a different product/process or to enhance synergy.

A - Adapt - alter, change function, use part of another element
Think about which parts of the product/process could be adapted to remove the probortunity or think how you could change the nature of the product/process.

M - Modify - increase or reduce in scale, change shape, modify attributes (e.g. colour)
Think about changing part or all of the current situation, or to distort it in an unusual way. By forcing yourself to come up with new ways of working, you are often prompted into an alternative product/process.

P - Put to another use
Think of how you might be able to put your current solution / product / process to other purposes, or think of what you could reuse from somewhere else in order to solve your own probortunity. You might think of another way of solving your own probortunity or finding another market for your product.

E - Eliminate - remove elements, simplify, reduce to core functionality
Think of what might happen if you eliminated various parts of the product/process/ and consider what you might do in that situation. This often leads you to consider different approaches.

R - Reverse - turn inside out or upside down.
Think of what you would do if part of product/process worked in reverse or done in a different order. What would you do if you had to do it in reverse? You can use this to see from different angles and come up with new ideas.