You mention you're using a particle system. When do you create and destroy your particle system? And which fangame engine are you using? If you're using an engine like yuuutu, and creating your particle system on game start, but not destroying it on game end, then you're actually creating a new particle system every time you press R! Try just opening your game, saving, and just pressing R over and over and see if you can get it to crash really fast - if so you've got a memory leak on your hands.
Also, how big is your project file (the gmk or gm81 file)? Just so I can imagine how much stuff is actually in your game, to see if that's becoming an issue. The effects wouldn't matter much, but large, animated sprites and backgrounds can really eat at your memory consumption without you noticing. Images are stored compressed in PNG format but are uncompressed when loaded into memory, dramatically increasing the amount of space they take up. As a quick example, a plain 800x600 black rectangle is just 4kb big as a PNG, but it's 1MB as a sprite! Music is another big one, especially if you store your music as WAV files (don't do that!).