ride the bike until the offending part fails, it's amazing how many months you can squeeze out of parts that seem about to fail
I rode a front wheel with rims so worn that they exploded (scaring some armed coppers a lot)
I regularly eke out brake blocks until metal on metal
I'm almost certain the bottom bracket is about to fail at the moment, and I very think the freewheel is on the way out, i stopped on a ride home late at night because the drive train was spinning freely, i actually turned it with my hands, after getting back on and wiggling a bit it caught again and off I went, now it seems like something I imagined
point being when you think you've pushed something to the limit but can't or won't buy the new bit, keep and you'll get months more riding, it might not even fail when you're doing 20mph+ and your money will go much much further
I well remember having wheels rebuilt a few years back just because they were getting noticeably worn, the LBS is terrified to look at my bike now
But it still goes (doesn't always stop as quickly as it should mind)