The share capital is normally use to finance the company expenses, especially at the beginning, when it has little to no earnings, in order to keep it active. However, it is possible that said share capital will be spent in its entirety. One possibility is to increase the share capital.
In that case, you need to modify the entry in the registry of the company to reflect the change in share capital and, optionally, the shareholders structure (in case external investors will enter the company, for example). This process requires an administrative procedure and the payment of a state fee, but there is no problem in doing so.
In case of a shareholder re-distribution, it will be necessary for the new partners to make a trip to Estonia to visit a notary.