At any time you can change your service offering of any VPS. You can increase or decrease computing power of your VPS to correspond your current needs. To do it go to "Status of services" and press button "Change service" for VPS you want to change.
Service offering change involves activation of the VPS on the minimum period, which is 1 month. The balance left from the previous service offering will be taken on discount in the cost of new one.
For example you have purchased a xsmall-VDS for one month (96 UAH). After 15 days of usage you decide to increase your computing power to small-VDS (240 UAH). The balance left for your current computing offering is 96/30*15=48 UAH. So you need only 240-48=192 UAH on your account to change your computing offering.
There is no fee for changing computing offering. You can do it as often as you need to.
In the field "The proposed amount of refill (UAH)" you can see calculated sum you need to add to your account if there is not enough money.
When you press Done your VPS will reboot. After it is rebooted it will use new computing offering. Reboot process can take some time depending on operating system of your VPS. Please be patient.