A bond is a contract between the defendant, the court, and the surety agent (bondsman). The contract states that the surety will put up a certain amount of money to guarantee the defendant's release from jail. In return, the defendant agrees to appear in court when ordered.
If the defendant fails to appear in court when ordered, the Judge can issue an alias capias and the bondsman could lose their money.
At your first appearance, which occurs within about 24 hours of arrest, the Judge may set a monetary bond. You may have posted your bond prior to your first appearance. Or perhaps you will be released on a non-monetary bond, such as an ROR (release on recognizance) or Pretrial Services/Pretrial Release.
If the Judge imposes a monetary bond (the most common type of bond), you will be required to either post the full amount (cash bond) or hire a bail bondsman who will post the bond (bail bond) in exchange for a premium, which is typically 10% of the bond. This is the bondsman's fee and is non-refundable. If you post a cash bond, the amount can be refundable upon the close of your case, provided you appear at all necessary court appearances.
If you post a bail bond, then you have signed a contract with the bondsman. The bondsman has agreed to post your bond based on the information available at the time. That is, the charge or charges that you were arrested for. If those charges change, so do the terms of the contract.
If at arraignment (or any time thereafter) the state files additional charges, the Judge must then set a bond on the new charges.
For example, if you are arrested for grand theft but at arraignment, the state files one count of grand theft and one count of tampering with an anti-shoplifting device, the Judge will have to set a new bond on the new charge. This usually requires you to submit proof that your bondsman is willing to remain on the bond even though you are now facing a maximum of 10 years in prison, as opposed to only 5.
There must be a "change in circumstances" in order for the state to seek an increase in bond. Adding charges, or increasing the severity of a charge (felony battery to aggravated battery) is a sufficient change in circumstances. The state may ask the Judge to increase the bond for that reason.
If the state is seeking a bond increase, they must provide three hours notice to the defendant. This is required by law. The state cannot ambush you at arraignment (although they do). But the defendant has a right to three hours in order to prepare.
If the surety is willing to stay on the bond despite the change in charge, or additional charge or charges, they can usually submit an affidavit to the Judge stating their willingness to remain on the bond. In 99% of bond review matters, this affidavit is sufficient. In fact, if I know ahead of time that the state will be seeking a bond increase, I will contact the bondsman and get an affidavit before we go to court so that I can submit it to the Judge immediately.
If the state is classifying you as a "career criminal," such as a Habitual Felony Offender (HO) or Prison Releasee Reoffender (PRRP), they can seek a bond increase. That's because under these statutes, you face more time in prison per charge than if you were not enhanced. Since the exposure is greater, thus the risk of flight is greater (state's logic, not mine). Sometimes judges will grant motions to increase bonds when a defendant is enhanced. However, some judges will allow a bondsman to submit an affidavit and the judge will not increase the bond.
Remember - the status of a bond is entirely up to the Judge. The state can argue and ask for whatever they want, but it is totally within the power of the court to set a bond, revoke a bond, or increase a bond.