You can look for a troll witch or shaman that has Transfer Regeneration (or anyone that qualifies for the spell) so they can regenerate your severed limb.
You can look for a cleric for Regenerate, and donate up to 910 gp (7 * 13 * 10 gp) to his church. A high level cleric may be rare depending on your campaign setting though.
However, if at first level your character already lost a limb, you should consider looking at the optional rules for Called Shots, we have 3 types of damage caused by aiming at a specific body part:
1) Called Shot: An attack aimed at a body part that deals fewer than 50 points of damage results in a normal called shot. Called shots inflict either minor penalties or temporary inconveniences.
2) Critical Called Shot: When a called shot is confirmed as a critical hit but deals fewer than half the creature’s hit points of damage (minimum 50), a critical called shot results. Critical called shots can cause ability damage, bleeding, and other serious effects.
3) Debilitating Blow: A called shot that deals half the creature’s hit points of damage (minimum 50) or more (whether a critical hit or not) results in a debilitating blow that has extra effects. A debilitating blow inflicts major consequences and potentially permanent consequences.
Losing an eye, losing an arm or leg, have your head separated from your neck are all major consequences of debilitating blows. For arms specifically, not only it has to be a debilitating blow, but the target has to fail his saving throw by at least 5 points:
Arm Debilitating Blow: A debilitating blow deals 1d6 points of Dexterity damage and 1d6 points of Strength damage. The blow renders the arm useless until healed unless the target succeeds at a Fortitude saving throw. If the saving throw fails by 5 or more, the arm is severed or otherwise mangled such that only regeneration or similar effects can repair it. The target also suffers the effects of a called shot to the arm (if the arm remains usable) for 2d6 minutes.
Yes, these are optional rules, but they do give us an insight at how serious a severed limb should be on the game system. Potentially aimed at higher levels and not the first few character levels, as few creatures can deal more than 50 points of damage in a single attack. So things that can routinelly sever a limb off should be rare, unless it was done outside of combat (a tortured prisioner?).
The Regenerate spell was ruled as 7th level spell assuming that very few things at the lower levels in the system can sever a limb. A GM that decides to house rule that PCs can get their limbs severed at lv1 by thug with a sword that roll a critical hit, should consider adjusting the spell level aswell. Or create an alternative such as Regeneration, Lesser to allow low level characters to recover their limb's function if they are able to at least attach the limb back together.
Otherwise the system will strongly benefit characters that focus on critical hits and weapons with high critical range (kukri, scimitar) and roleplaying effects that will have real effects on the game system, like saying "I am aiming at his arm" before rolling an attack roll.
Lastly, a Cracked Pearly White Ion Stone would be a cheaper alternative, if the character had one prior to losing his limb.