I am slim enough and do not want to lose my weight but I do bicycling for some hours three times per week and cannot avoid it! How can I control my weight through doing this? I do some other sports like swimming and squash two times per week too.
If you eat enough food to offset the energy you spend cycling, you won't lose weight.
One basic approach might be to estimate the number of calories you're spending (there are several online calorie estimate tools for cycling out there on the internet), and make sure to eat that much additional food per day. Track your weight, and adjust the amount of food you're eating if you start gaining or losing too much.
If you're already eating a healthy diet, you can just eat proportionally more of whatever you're already eating.