Here's a computer method:

Step 1.
Someone analyses a lot of text (e.g. a huge number of web pages and/or books)
and publishes a data file like a dictionary. The entry for "orchid" might list about
a hundred or more related words and phrases, with a score beside each one to
show how closely connected it is. Maybe there's something like that out there
already.

Step 2.
Someone writes a program that uses that list along with their own private input.
It starts with words from their own input, finds related words using the list,
and maybe does more steps, finding words related to those words and so on.
At each step it can choose the highest-scoring words or phrases, or choose
words and phrases at random with higher-scoring ones more likely to be chosen.

At the second step it might assign negative weights to the original words (and so on).
That's counter-intuitive but I think it's similar to how the human brain works and may
be worth a try.

Here's a different method, using the human brain:

Select two phrases from your input, at random. Think up an idea that
is connected to both of them. Repeat this exercise many times over a number
of months. At first it may seem mechanistic, but eventually it gets you
thinking in a different way (the way solving cryptic crosswords does),
as well as increasing the salience of the input. Later, interesting ideas
may bubble up from the subconscious at odd times.

If you have difficulty thinking up an idea, lower your standards:
the idea is allowed to be silly and useless and is allowed to be only
loosely connected to the input. Lowering the standards in this way
is an important step in creative thinking. Sometimes a silly idea
turns out to actually be useful, or else to lead to another idea that's
useful.