For almost all of history and in almost all places, this is just an issue of finding your best risk-free investment because interest rates have historically been higher than inflation (positive real interest rate). However, in Europe especially, almost all fixed-income securities have negative real interest rates and many investments now have negative nominal interest rates (they pay negative interest). As a result, you don't really have any places to hide. Here are your options.
- Move your money to another country. This can be hard, and will also cause you to bear currency risk.
- Buy financial securities with some risk. You can put money in the stock market or buy fixed income securities that have enough risk that their yield is higher than the expected inflation rate. Of course, both of these have the possibility of losing you money.
- Spend the money on real assets. When prices go up, stuff you buy will tend to go in price as well. Gold, real estate, art, etc. Anything that has a selling price approximately equal to its buying price. Of course, these will all have risks as well.
Or you can just lose money. This low or negative interest rate regime will punish savers. It's the same thing that happens during monetary stimulus. The idea behind a stimulus is to punish those who save in an attempt to make people spend more instead. Your intention is to save, so you are going to be punished if you do.
Since you plan to use the money in a few months, your best bet is probably just to keep doing what you are doing. You won't loose that much.