I think we should spend the money on/for a sports club with new gym and bar facilities.
As usual, the absence of context allows us to invent intentions for the speaker or writer, and from these inventions or assumptions flow our interpretations of the meaning of the sentence.
Here are some assumed intentions, and the resulting meanings of the sentence.
I think we should spend the money on a sports club with new gym and bar facilities.
Assume: A conversation among people trying to decide how to use the money from a bequest. Among the choices under discussion is a sports club. If the money is not spent on a sports club, it will be used for some other purpose.
Interpretation: "On" simple connects
the money to an intended use.
Let's spend it on this. If not, let's spend it on that.
On points to the destination of the funds.
---------------------------------------------------------------------------
I think we should spend the money for a sports club with new gym and bar facilities.
All of the above, both assumptions and interpretation, can be used again with
for.
New assumption: Money has been budgeted or allocated previously. It will be spent to create a sports club.
Interpretation: The sports facility should have, in the opinion of the speaker, a new gym and bar facilities. The speaker is advocating that the new sports club, in contrast with whatever facility it will replace, will have features not previously present.
The second assumption and interpretation might also work with
on.
Conclusion: without more context and background, the two prepositions are interchangeable in this sentence. Neither one restricts the meaning. Money should be spent, according to the speaker. Either preposition can point at the use to which it should be put.