Applying twice for Schengen Visa

Visa and length of stay are two separate (albeit obviously related) issues. Short stays in the Schengen area are limited to 90 days in any 180-day period (see the relevant discussion) so if you stay there for three months, you need to be somewhere else for three more months before you can come back on a short-stay visa.

Depending on your exact situation, you might or might not be able to get a new Schengen visa but it will not open any right to stay longer. Some people can visit the Schengen area without visa, others have short-stay visas valid for several years but they all have to abide by this rule. It also doesn't matter which country issued the visa or if you get a new short-stay visa from a different country than the one that issued your first visa.

The only way to stay longer legally is to obtain a national long-stay (type D) visa or, in exceptional cases, a limited territorial validity visa (and exceptional means exceptional, it's intended for diplomats participating in talks at the UN and these sorts of things).

If you do want to apply for a new visa, two things are worth noting:

• You can't apply for a new Schengen short-stay visa if you already have a valid one, you first have to get the old one invalidated by the country that originally issued it.
• If you already used up your 90 days or submit an itinerary that would run afoul of that rule, your visa should be denied. This denial will be registered in a database and the visa application fee will not be refunded so trying on the off-chance that it might work is not necessarily a good idea.