In most cases, small cracks can be painted over with 'pool-paint', which is specially made with a thick, durable rubber base that will seal hairline cracks for some time. If you have opened cracks that are causing allot of water loss, the solution may require applications or excavations that is better handled by specialists experienced in pool repair. In this manor, you can also receive a written guarantee.

There are multiple things to consider when re-plastering a pool, including the expansiveness and severity of the damage your pool has. Some pools have plaster cracks in a few places that can merely be repaired by patching up the damaged areas. If you can post a photo or video of the offending area, I'd be happy to give you a more concrete answer. However, one thing to avoid is painting over the problem since this solution is extremely temporary. A lot of pool owners try this and don't think about paint durability under gallons of water and pool chemicals.