When I have to make some sort of payment that has to be funded...

When I have to make some sort of payment that has to be funded by selling some shares, I use it as an opportunity to do some culling.

Print out your current share holding and go over all of them. Sell the losers. Look at every company, is it going up, down or sideways. If you were buying today, would you buy it? Don't worry if you take a loss, just get rid of the losers and keep the good ones. Use a fresh eye and be critical. If it has managed to escape the stoploss, now is the time to sell.